Graf Zeppelin I


Graf Zeppelin. Flugzeugträger. Stapell.: 8.12.1938 B 676 (R IX E 7845)

Flugzeugträger "A". Baustadium Aufgen. am 14.9.1937 Deutsche Werke Kiel

Plans for a shipped-based air force started soon after Hitler became Chancellor in 1933. The first plans were limited to supplying the existing battleships and cruisers with reconnaissance seaplanes. On March 12th 1934 the first requirements the future aircraft carrier was given. Within a year the design study had been completed. The model used was the British Courageous class of carriers. On June 18th 1935 the signing of the British-German naval agreement set the future strength of the German Navy at 35% of the tonnage of the British fleet applied to all classes of ships. This opened the way for building the first German aircraft carrier. Based on British tonnage of the time, 38,500 tons, this allowed for two ships of 19,250 tons. Officials were sent to England to attend the Navy Week where HMS Furious was opened for visitors but little was learned. More successful was a German Commission allowed to visit the carrier Akagi in Japan where they were given 100 copies of the blueprints of the air deck facilities. However, the Japanese neglected to tell them that the carrier was about to be completely rebuilt and the plans were obsolete.

At the end of 1935, when the design of the carrier was mostly completed, it received the consent of the commander of the navy. On 16th November 1935 the order to build the ‘A’ carrier was given to the Deutsche Werke Kiel AG. At that time most of its resources were engaged in building other warships and its slipways were occupied by ships under construction. Therefore construction was delayed until 28th December 1936 when it was possible to lay the keel on Slipway 1, twenty days after Battleship ‘E’ – the Gneisenau – had been launched from the same slipway. The slipway construction stage took two years. The ship was launched by Countess Hella von Brandenstein-Zeppelin, daughter of Count Zeppelin, on 8th December 1938 in the presence of Adolf Hitler. Work progressed during 1939 and by August it was estimated that the first tests could be carried out in June 1940 and the ship ready for service by the end of that year. When war broke out the Graf Zeppelin was 85%-90% completed. The engines and boilers were in place, the auxiliary machinery prepared though not yet installed and the 15cm guns were in place as well but lacked armoured shields.

The order for carrier ‘B’ was placed on 16th November 1936 with the Friedrich Krupp-Germania shipyard. The laying of the keel could not have taken place until the second half of 1938, after the heavy cruiser ‘J’ had been launched, because only one slipway (VIII) could accommodate the carrier. The date, 30th September 1936, given in some sources is invalid and probably a misprint. 30th September 1938 seems the most likely date. The construction of the ‘B’ carrier was intentionally slow because of the possibility of using experience gained from trials of the Graf Zeppelin in the ‘B’ construction. The planned launching was 1st July 1940 which did not take place as the order was cancelled on 19th September 1939. The ship had been finished up to the armoured deck. On 28th February 1940 Admiral Raeder ordered the dismantling of the hull. The ‘B’ carrier was never given a name. Peter Strasser is ascribed to the carrier by some sources but is entirely speculative and it is questionable that Hitler would have approved it even if it were on the list of proposed names.

After the start of the war, works on the Graf Zeppelin continued as planned for a while, but soon delays were caused by the extensive U-Boat building programme. [Carriers were always last in construction priority. Until 19th September 1939 the priority was: battleships, submarines, destroyers, cruisers, aircraft carriers.] In October 1939 Hitler allowed only the building of small ships and the continuing construction of five large ships, the Graf Zeppelin among them. It was the German conquest of Denmark and Norway that had an adverse effect on the ship’s fate. Defence of the long the Norwegian coast required many small ships and their construction became the priority. During a conference with Hitler on the 29th April 1940, Admiral Raeder proposed stopping all work on the carrier. Even if the ship was commissioned as planned at the end of that year, equipping her with guns would take another ten months, if not longer, and the installation of the fire control system several more months. (The original fire control system had been sold to the Soviet Union. In the end the AA and 15cm guns were removed and sent to Norway to be incorporated in the coastal defence system.) During a conference in July, Hitler referred to aircraft carriers saying that Germany must have “a cruiser with a flight deck”. Ludicrous as it was to start a new project when the existing carrier was almost complete, it was Hitler’s remarks that stopped all work on the Graf Zeppelin on the 12th July 1940 and the Design Bureau to prepare a design of an ‘M’ cruiser that could carry 14 aircraft. On the same day the Graf Zeppelin left Kiel for Gdynia (called Gotenhafen by the Germans). The ship remained there almost a year until Hitler’s decision to attack the Soviet Union on 22nd June 1941. Because of the treat of Soviet air raids the Supreme Command of the Navy ordered Group North to tow the ship further west by 19th June. The carrier left at noon 19th June and reached Stettin on afternoon of 21st June. There she was moored at Hakenterasse, remaining until German forces had penetrated far enough to lift the threat of air attacks. On 10th November 1941 she left Stettin to arrive a week later back at Gdynia. She was then used as a floating warehouse for hardwood under the name Zugvogel.

By the end of 1941, the crippling of the Italian fleet in Taranto, the Home Fleet’s interception of the Bismarck and especially the Japanese attack on Pearl Harbor had proved that ship-based aircraft were a fully developed and dangerous weapon. The Seekreigsleitung pressed for completion and putting into service of the Graf Zeppelin as soon as possible. The final discussion took place on 16th April 1942 at Hitler’s Wolfschanze headquarters. The results were as follows:

  1. Works on the hull and engines were to be completed by summer 1943.
  2. The only available aircraft types, adapted Bf 109 and Ju 87, required upgrading of the air facilities, especially installation of stronger catapults. Design, production and testing of these would take not less than two years so it was decided to modernize and adapt the existing catapults which would take six months. This gave the earliest possible time to complete the carrier as the winter of 1943/44. From the point of view of the Luftwaffe constructing a new carrier-based aircraft was impossible before 1946.
  3. The Luftwaffe would provide the Kriegsmarine ten fighters and twenty-two bombers to be used in the reconnaissance role. Designing a torpedo-bomber was opposed by Hitler who thought such aircraft were not useful.

On May 13th 1942 the decision was made to resume the construction of the Graf Zeppelin. Along with changes to the air facilities there were other alterations considered necessary as early as 1938/39 because of the developments in naval technology. The superstructure was obsolete. The existing mast had to be replaced with a heavier one fitted with a fighter command post and radars. The bridge and fire control centre covered with fragment-proof armour. A higher funnel shield was necessary to protect the fighter command post from smoke. The alterations resulted in a significant increase in weight that needed to neutralised to keep the ship stable. Bulges were added to keep the ship upright. The secondary role was to protect the ship’s interior from torpedoes. Parts of the bulges served as oil tanks. These additions improved the manoeuvrability and range of the ship. AA protection was also upgraded. The planned air component was composed of 28 Ju 87s and 12 Bf 109s.


The Supreme Command of the Navy expected that work would be completed by April 1943 with the first sea test performed in August. However, the last twelve months of construction were to be carried out at the cost of cancelling VVIIC U-boats at Deutsche Werk AG Kiel. As well as the Graf Zeppelin, five other ships were to be converted to aircraft carriers. Due to the shortage of workers and lack of material, especially steel, Hitler decided to cancel the conversion of existing warships and put the workers and material into building the aircraft carriers Graf Zeppelin, Seydlitz and Potsdam. Meanwhile, due to increasing air threat, the operation to move the Graf Zeppelin to Kiel was delayed. She finally left Gdynia on 30th November 1942. On 3rd December the convoy reached Kieler Forde and the Graf Zeppelin anchored to the Heikendorf roadstead. On 5th December she was put into the Deutsche Werk floating dock where work on the bulges started immediately. At the same time work on the engines room was started to make the two inner shafts and their propulsion system operational allowing the ship to make a top speed of 25 to 26 knots. The objective was to finish the carrier in the autumn of 1943. On 30th January 1943 Hitler ordered all capital ships to be put out of service and cancel the construction of those not yet completed. Grand Admiral Raeder described it as “the cheapest sea victory England ever won” and was the direct reason for him being relieved from duty. On 2nd February 1943 the construction of the Graf Zeppelin, on which the bulges were still being installed, was stopped for good. On April 15th Deutsche Werk shipyard were ordered to prepare the ship to be moved to Gdynia. After these preparations the carrier was towed out on 20th April, its destination now Stettin. There she was anchored on one of the forks of the Odra River and camouflaged to look like a small island. The initial plan of moving the ship to Pillau was abandoned because of a lack of adequate anchor ground. The end of the carrier came soon after the Red Army entered the territory of the Reich. First all the Kingston valves were opened and the ship settled on the bottom. Then a ten-man squad prepared the ship for blowing up with depth charges. On the 25th April 1945 at 6pm the order was given. Thick smoke issued from the funnel, proof that the charges had gone off as planned.

Graf Zeppelin II



Last photograph of Graf Zeppelin towed from Swinocijscie Poland to Leningrad. April 17. 1947.

In April 1945, Soviet troops found the carrier’s artillery had been dismantled, the installation of fire control equipment had not been finished and the electrical installations partially installed as well as the flight equipment. There was a complete engine room and the power station was fully operational. Among the explosives, ten depth charges had been set off in the engine room. Water had penetrated through small blow-holes, cracks and leakages and the ship settled on the bottom in water seven meters deep. Seepage was so slow the water in the engine room was lower than that outside the hull. By 17th August 1945 the ship had been examined by teams of the 77th Emergency Rescue Unit. The carrier lay on the bottom with only half a degree of list to starboard. On the starboard were 36 holes up 1.0 X 1.0 meters made by shells and fragments. All the turbines, boilers and power plants had been blown up damaging the nearby watertight bulkheads. One .8 x .3 meter hole had been blown in the underwater part of the ship along with a .3 meter crack. The propellers had been dismantled and placed on the flight deck to minimize electrochemical corrosion of the hull. The aircraft elevators had been blown up as well. The ship was raised by simply sealing the underwater hole and crack and pumping out the water. Ten longitudinal and twelve transverse bulkheads had to be sealed to give the ship the necessary buoyancy. Cracks above the waterline and portholes were sealed with wielded metal sheets. Due to extensive damage and time pressures damage to ship’s deck were not mended. After the repairs were completed the ship was towed to Świnoujście, the former Kriegsmarine base known as Swinemunde. On 19th August the hulk was included in the Soviet Navy as a spoil of war. At the Potsdam Conference (17th July until 2nd August) the first agreement was reached on how to dispose of captured German surface vessels. On 23rd January 1946 an Anglo-American-Soviet committee was formed to deal with these matters. All combat and auxiliary vessels were divided into three categories A, B or C. The Graf Zeppelin was given to the Soviets by lot and came under category C – ships sunk, damaged or unfinished that required over six months of repairs using the resources of German shipyards. It was the recommendation of the committee that category C ships should be scuttled in deep water or dismantled by a given date. Admiral Kuzniecov requested to repair the Graf Zeppelin for use as an experimental platform for the construction of Soviet aircraft carriers. Initially he was given approval for the Baltic shipyard in Leningrad to carry out the necessary repairs; however the authorities chose the simpler option of complying with the terms of the allied agreement. On March 17th 1947 a resolution was passed that all category C vessels were to be destroyed in 1947. The command of the Soviet Navy had managed to convince the government to run durability tests on the vessels.

From 2nd February 1947 the Graf Zeppelin was classified as experimental platform PB-101. The destruction was to be carried out in a manner that allowed the collection of experimental data and experiences. A special committee head by Vice-Admiral Rall was formed and ordered to sink the carrier while testing its resistance to aerial bombs, artillery shells, and torpedoes in two variants, static and dynamic. Static meaning that the munitions would be placed in the ship and detonated and dynamic that they would be delivered by simulated attacks. The detonation of mines at various depths and distances from the ship was also considered. Between the tests teams of scientists would be sent aboard to assess the effects of the explosions. They were allowed to conduct minor repairs to stop the ship from sinking too soon.

At 2.45 pm on 14th August 1947 PB-101, as she was now known was pulled out onto the out roadstead of Świnoujście from where she was escorted by various vessels to the five mile square designated as the test area. Due to draining of three starboard rooms in the bulges she had a 3 degree list to port. When she arrived on the evening 15/16th August if was found that she could not be anchored. One of the main anchor chain links failed and the light kedge anchor could not prevent the ship from drifting. This was to affect the final outcome of the testing.

The first tests were carried out on the morning of 16th August. First a FAB-1000 bomb was exploded in the funnel along with three FAB-100 bombs and two 180 mm shells set under the flight deck. For the second test a FAB-1000 bomb was detonated on the flight deck. For the third a FAB-250 was set off on the flight deck and two 180 mm shells on the upper hangar deck. For the forth a FAB-500 over the flight deck set on a 2.7 meter high tripod, a FAB-250 on the upper hangar deck, another on the flight deck and a FAB-100 on the C deck. The fifth and last of the series, a FAB-500 and FAB-100 detonated on the flight deck with part of the bombs set deep in holes cut in the deck to simulate penetration.

The funnel was ripped open down to the flight deck but the island was not damaged, with the shockwave failing to deform the smoke ducts. No increase in pressure in the boilers was reported and on the armoured gratings an intact spider’s web was found. Of the three FAB-100 bombs detonated on the flight deck the most damaging was the one not set in the deck. The shockwaves of those set in deck were directed down into the hangar. The 180 mm shells caused various damage, the most effective being mixed armour piercing high explosive.

After the first series of tests an air raid was carried out on the ship by 39 aircraft from the 12th Guards Mine Torpedo Division and 25 Pe-2 dive bombers. On the day of the test there were only 100 P-50 exercise bombs available in the entire 4th Fleet instead of the 156 required. Therefore only 24 Pe-2 crews could perform the bombardment. Two nine plane flights dropped their payloads on the leader’s signal, the rest individually. A white 20 x 20 meter cross had be painted on the flight deck with arms 5 meters wide. The first group dropped 28 bombs from a height of 2070 meters, the second 36 from about the same height and the third attack carried out individually another 24 bombs. Three aircraft were forced to emergency dump their ordnance. The effects of the attack on what was a ‘sitting duck’ were farcical. Of the 100 bombs dropped only six hit the target, and there were only five marks on the flight deck. (Soviet pilots claimed there were eleven hits, some of the bombs having struck already damaged areas.) The test failed to give any useful information. The P-50 bombs were too small causing 5-10 cm dents in the flight deck and blew a hole about one meter in diameter in the starboard bulge. The pilots complained about poor visibility.

Another series of static explosions followed. After the forth series the entire island was wiped out and the upper hanger seriously damaged. The effect of the fifth series was the most spectacular. A FAB-550 bomb on the flight deck blew a three meter hole and a FAB-100 bomb in the hanger demolished all the light walls and destroyed the equipment. That concluded the static tests and preparations for the testing of underwater munitions where begun. On 17th August the weather bean to worsen and the carrier started to drift towards the shoals. There was the possibility that the ship would drift into waters too shallow to sink her. Rall decided to abandon the testing and finish off the carrier with torpedoes. The planed bombardment by cruisers had been cancelled because of an accident in one of the main turrets of the Molotov. The usage of the 180mm artillery was banned in the entire Soviet Navy for the year 1947. Three torpedo boats and the destroyers Slavny, Srogy, and Stroiny were summoned. The torpedo boats arrived first. The first run by TK-248 was unsuccessful, the torpedo passing under the carrier’s keel. After 15 minutes a torpedo fired by TK-503 hit the starboard side near frame 130. The explosion destroyed the bulge but the armoured belt remained unscathed. After an hour the destroyers arrived and the Slavny hit again the starboard side near frame 180 where there was no bulge. The carrier began to list to the twice damaged starboard. After 15 minutes the list reached 25 degrees, and the ship started to trim to bow. After another eight minutes the Graf Zeppelin with a 90 degree list 25 degree trim to bow slipped below the surface. The date was 18th August 1947.

The results of the tests were kept secret and the allies only informed that she had been sunk. The gap between the summer of 1945 when she was raised and March 1947 when her fate was decided remains a mystery. The German Admiral Ruge claimed in a book that the carrier capsized while being towed from Stettin to a Russian port due to the stowage of steel sheets on the flight deck According to gossip circulating in the Baltic Fleet published by Marek Twardowski in a magazine article, in 1946 the ship was towed to a Leningrad shipyard to be prepared for service. The authorities found this a welcome occasion for the transport of heavy loot which was placed on the flight deck because the damaged elevators prevented the stowage in the hangers. Placing a heavy weight on the flight deck made the ship unstable and she capsized in the shallow fairway. Most of the goods from the flight deck fell in the water, whilst those stored below caused serious damage to the bulkheads and braces. Raising the ship was not difficult but she was no longer suitable for reconstruction and had to be sunk to cover the accident. This supports the account of Ruge but is most probably untrue.

The Battleship Race Won and the Strategy Lost

Btlshp USS Arizona NARA-5900075

USS Arizona Built in 1913 and was the second and last of the Pennsylvania Class “super-dreadnought” battleships and primarily served stateside during WWI. She was part of the escort of the USS George Washington that carried President Wilson to the Paris Peace Conference on December 13, 1918. 31,400 tons and required a crew of 1,385. She was sunk on December 7, 1941 at Pearl Harbor by the Japanese leading the United States into WWII. 1,177 lives were lost when the Arizona was destroyed.

In 1897 the US navy was ranked as the sixth most powerful after Great Britain, France Germany, Russia, and Japan. The naval appropriations of 1898 resulted in the US navy moving up to fourth position by 1902; and by 1908 it had only Great Britain ahead of it as the supreme maritime power. Between 1895 and 1910, in a span of 15 years, a new navy had been created in consonance with the Mahanian strategy of the battle between capital ships. Much of this drive to build bigger battleships was the result of international competition rather than an absolute need. The rapid arming of Japan and its conquest of Manchuria had pleased the American government as it was quite ambivalent on whether the main threat to the US in the Pacific came from-Russia or Japan. The defeat of the Russian main fleet at Tsushima by Admiral Togo alarmed the Americans into a clearer understanding of where danger lay. Much of the confusion in Washington arose as a result of intense lobbying from London, which pushed for American rearmament as an additional bulwark against the Kaiser’s building of a High Seas Fleet. During this phenomenal growth period, the same questions reappeared. Did a strategy drive the rearmament, or did the newly created force drive strategy? On record we have only two documents-Plan Black and Plan Orange-to work from to solve this conundrum. Plan Black can hardly be said to fall within the ambit of strategy. It would be difficult even to consider it to be relevant at the operational level. It was, at most, a tactical plan for a onetime operation, involving the interception of an alleged German intention to occupy Culebra with a seaborne invasion force and then attack the east coast. Considering the relative strength of the German and British fleets and the need to support the centre of gravity in central Europe, this was not a realistic course of action the Germans could possibly have thought up. Even if we discount the fact that in 1905 naval planners could not have forecast what the submarine would do to change naval warfare in the next decade, Plan Black could at best be described as an alibi for what had already been decided-the rebuilding of the US battle fleet.

Plan Orange, on the other hand, was acutely perspicacious. It described the plan to recapture the Philippines through a central Pacific thrust after its capture by the Japanese in the initial stages of a war-a scenario duplicated almost exactly 40 years later. The great dilemma was whether the fleet should be concentrated in the Pacific or the Atlantic, or split into two, each half being considerably weaker than either Japan’s or Germany’s navy. This dilemma was partly solved by the opening of the Panama Canal in 1914, an achievement which took over a decade. The idea began with the US-inspired revolt of the people of Panama against Colombian rule in 1903, supported by the US navy. To dominate the Pacific from Washington by building the Panama Canal, enabling a concentration of force, is certainly grand strategy. But was it all part of a plan? Perhaps a person like Theodore Roosevelt was capable of thinking out grand strategy on that scale, but there is little evidence that the navy department was thinking along these lines. Underlying the frantic battleship race that preceded World War I were the varying rates of economic growth of the countries involved and their standing as world powers based on their economic might.

If the US was catching up with Great Britain in the number of battleships, it still had quite far to go to develop a comparable maritime strategy. In 1900 Great Britain already had a maritime strategy worldwide, to protect her far-flung empire as well as to ensure peace on her terms anywhere on the world’s oceans. To give Whitehall the ability to exercise command of the Royal Navy worldwide, Britain had established global undersea cable links, that were later backed by HF stations, permitting a ship in any part of the world to be within easy communication distance of a powerful radio station. This complicated communications tentacle, which really was the heart of Britain’s ability to react to any situation on any of the world’s oceans, had no comparable equivalent in the US. In fact, if force levels and communications are judged to go hand in hand, it was not until the late 1950s that the US had a comparable worldwide communications system for her navy.

After the Battle of Tsushima, when Britain signed an alliance with Japan, there was much heartburn in Washington. Under the terms of the alliance, Britain would remain neutral if Japan fought one power but would join Japan if the Japanese had to fight two powers simultaneously. Britain made some concessions to the US to placate Washington, but both sides kept a wary eye on each other’s battleship-building programmes. By 1905 Mahan was accepted by the navies of the US, UK, Germany, Russia, and Japan as the source of all maritime wisdom. France alone remained aloof from a total acceptance of Mahanian strategy. Since all of these nations viewed the big battle as the final arbiter of sea use, a battleship-building contest began which was limited only by the governments’ ability to pay for them. The blind adherence to the cult of the battleship was responsible for the US entering World War I without any credible idea on what the navy would do in such a war. In any case, until 1910 the US visualised that Japan would be the likely threat. The reason for this presumption is not clear other than that Japan was the nearest Asian power with a large number of battleships; there was no economic rivalry, no conflict of interests. An alleged Japanese attempt to occupy a port in Mexico on payment was resisted and the Japanese backed down. Perhaps with the hindsight of what we know about World War II, we may tend subconsciously to support the US naval view that Japan would be the next enemy, but it must be remembered that much of the Japanese desire to expand into South East Asia, and conquer the Philippines en route, lay three decades away. The Americans faced only one threat in World War I, and that was the German submarine, a weapon they had no idea would affect the course of the war to the extent that it did. If the miscalculation on the future role of the submarine was painful, the anticipation in Washington that the submarine would have to fight according to the existing laws of war was a downright blunder. This led to the Lusitania carrying almost 2,000 passengers along with 4 million rounds of small arms ammunition-a deadly combination. The responsibility for the destruction of the ship must lie squarely with US naval authorities who permitted a war-like act by a large and vulnerable passenger ship.

Many have questioned Britain’s maritime strategy in the Royal Navy’s approach to World War I. The strategy in part was indeed thorough and well thought out, particularly the blockade of Germany and the refinement of the co-operation between the navy and the ministry of economic warfare. The rest of the strategy-the role of the main force, the battleship fleet-is what has come under criticism. Judged against the yardstick of the criticisms levelled against British strategy, the US maritime strategy must surely take a beating. At the beginning of the war, before Admiral William S. Sims took up his post in London, the Chief of Naval Operations (CNO) is reported to have told him that as far as the US navy was concerned, they would just as soon be fighting the British as the Germans. 9 If we read more into this, the failure of the US navy to fashion a more serious strategy against the Germans than Plan Black is quite understandable, since the European enemy was indeterminate. But this understanding must then be validated by a US naval strategy for war against Great Britain. Such a plan, if it existed, had yet to be publicised although war-games played before 1914 reportedly had the Royal Navy in the role of the `enemy’.

An admission of the absence of a US maritime strategy against any European power comes from the 1916 Naval Appropriations Act put up to the Congress. The earlier request, made in 1915, for a massive battleship force to meet any possible combination arising from an alliance between two powers from among Britain, Germany, Austria and Japan had been hobbled by the politics of the presidential elections. Nevertheless, the Act when it was passed in 1916, laid down the foundations for a navy that was meant to challenge the supremacy of the British navy after World War I. For what purpose this supremacy was to be challenged is most unclear. No American commercial interests would have prospered by facing off the British navy in any part of the world-at least at the end of World War I. If there was a link between the political goals of the US and the strategy of its navy up to 1914, it has yet to emerge.

In the meantime, the only worthwhile American maritime strategy during the course of the war had to be implemented by cunning and subterfuge against the wishes of the CNO, Admiral William S. Benson, the officer who superseded 26 admirals to become CNO. This extraordinary event occurred when the senior admirals revolted against the overweening powers of the secretary of the navy, Joseph Daniels. The contribution of the US towards winning World War I was to supply both men and material in dozens of convoys safely through U-boat waters by escorts which had to be diverted from screening the battleships. Eventually the US built almost 400 escorts after pressure from Admiral Sims in London had convinced the navy department that the continental war in Europe was the main theatre and that an American contribution to it would require only anti-submarine escorts from the US navy. In all, 1,200,000 men of the American army and Marines were landed in France. Equally important, not one American battleship fired a shot in anger throughout the war. The five battleships of the US navy attached to Admiral David Beatty’s fleet arrived long after Jutland and replaced five older battleships decommissioned for the purpose of providing crews for ASW vessels.

When the war ended, a considerable amount of anti-British feeling existed among the American delegations that went to Paris. Much of this was caused by Britain’s firmness in imposing the blockade against Germany where many items produced in the US had been declared contraband. At the same time, the British had been reasonable in releasing those American items which were used for munitions if they were convinced that the Germans could have easily replaced the US product with an equivalent. Nevertheless, the Americans were convinced that the British intended that a regime should be enforced on the world’s oceans where trade would proceed only with the permission of the Royal Navy. The chief weapon of negotiations for the Americans was their unwillingness to concede the primary position to the Royal Navy in battleship tonnage. For the British it was their threat to scuttle President Woodrow Wilson’s League of Nations. The stalemate continued and no solution was found until 1922, when the existing ratios of battleship tonnage for Britain, US, Japan, France and Italy were finalised at 5:5:3:1.75:1.75.

Dutch Navy


De Zeven Provinciën was a Dutch ship of the line, originally armed with 80 guns. The name of the ship was also written as De 7 Provinciën. The literal translation is “The Seven Provinces”, the name referring to the fact that the Dutch Republic in the 17th century was a confederation of seven autonomous provinces. The vessel was originally built in 1664-65 for the Admiralty of de Maeze in Rotterdam, by Master Shipbuilder Salomon Jansz van den Tempel.
The ship served as Admiral Michiel de Ruyter’s flagship during the Second Anglo-Dutch War, taking part in the hard fought Dutch victory in the Four Days Fight, the bitter defeat at the St. James’s Day Battle, and acting as a command post as well as blockading the Thames during the Raid on the Medway. The vessel gave a good account of itself throughout the war, although it was partially dismasted during the Four Day’s Fight.

De Ruyter used De Zeven Provinciën as his flagship during the Third Anglo-Dutch War of 1672-1673. The ship served in all four major battles against the combined English and French fleet, fighting in the Battle of Solebay, the first and second Battle of Schooneveld and, in possibly its greatest moment, at the Battle of the Texel.
In 1692, the ship, now armed with only 76 guns, fought at the Battles of Barfleur and La Hogue during the War of the Grand Alliance. The vessel was severely damaged during the fight and, in 1694, De Zeven Provinciën had to be broken up.
De Zeven Provinciën measured, in English Feet, approximately 151 ft long by about 40 ft (12 m) wide by a little over 15 ft (4.6 m) deep. It was originally armed with 12 36-pdrs and 16 24-pdrs on the lower deck (although this had been changed to an all 36-pdr battery by the time of the Third Anglo-Dutch War), 14 18-pdrs and 12 12-pdrs on the upper deck, and 26 6-pdrs on the forecastle, quarterdeck, and poop deck.

Emerging from success after success won by fleets of “Sea Beggars” during the Eighty Years’ War (1568-1648), the Navy of the “Generality” of the United Provinces should have been one of the strongest in the world entering into this period. In fact, it had been badly neglected by the States General in the final years of war with Spain. In 1650 it was still primarily a fleet of armed merchantmen rather than purpose-built warships, though it was by far the largest such fleet in the world. The merchant marine of Holland alone employed nearly,000 seamen, without counting tens of thousands more experienced seamen of the vast Dutch fishing fleets. The Dutch fleet had a major structural flaw beyond simple neglect and non-purpose-built ships: there was no “Dutch Navy” per se. Instead, there were five provincial admiralty colleges operating out of Amsterdam, Holland (“North Quarter”), Friesland, the Maze (Rotterdam), and Zeeland. Each admiralty supported a discrete fleet maintained by its own naval establishment. Ships of these five establishments were supplemented, but only ad hoc, by powerful armed merchant fleets owned by the Dutch East India Company (VOC),West Indies Company, and smaller joint stock companies. Some Netherlands cities maintained small navies (directieschepen), used to escort only their own municipal ships in convoy. All this represented the overall radical constitutional decentralization of Dutch national life and politics. This was in striking contrast to the centralized and centralizing naval administrations of the main sea rivals of the Dutch: England, and later, France. Worse still for the Dutch, in the late 1640s the five admiralty colleges sold off many of their ships in response to the end of the long war with Spain. As tensions rose with England, in 1651 the States General reversed course and voted funds to build a navy of 226 warships, up from the extant number of just 76. However, this measure produced only three additional warships by the start of hostilities with England in 1652. Moreover, the largest of existing Dutch ships mounted no more than 50 guns. That meant England had 14 ships as big as or larger than even the most heavily armed Dutch man-of-war. English guns were also heavier, in addition to being more numerous, with longer ranges and greater power as ship-smashers.

One short-term result of the vote was the outbreak of the First Anglo-Dutch War (1652-1654), even though the Navy was then divided by mutinous crews and political quarrels between the Orangist Admiral Maarten van Tromp and the republican Regents of Holland. The weakness showed at Kentish Knock, where nine Dutch ships deserted and Admiral Witte Coneliszoon de With was refused boarding by other ships after losing his flagship and taking to the sea in a ship’s boat. The Dutch Navy suffered from other physical disadvantages in addition to having smaller and undergunned ships. Its harbors did not lie windward of the enemy, as did English ports, and it was forced to disperse to multiple harbors by the lay of the Atlantic coast of the United Provinces and by a strategic need to protect more important Baltic routes. The poor quality of Dutch ships was quickly revealed in the first of three Anglo-Dutch wars, as Dutch ships were dismasted and holed in large numbers by heavier English guns and superior tactics of the English fighting instructions. The States General ordered the fleet rebuilt after the war, laying hulls for 60 men-of-war by early 1654. However, complaints of admirals about the smallness and poor design of even these new ships were ignored. The Regents of Holland thus continued to build numerous small, undergunned warships, with the largest still mounting just 54 guns. This probably reflected the much higher interest of merchants in seeing construction of fast convoy escorts and in coastal defense, over creation of a true battlefleet. Crucial reform was finally introduced following the war. The States General proclaimed that new ships belonged to the Generality of the United Provinces, not to the five independent admiralty colleges. The latter were thus denied the usual temptation to sell off warships for short-term profit upon the end of the most recent conflict. Slowly, though unsurely, a national Dutch Navy began to take shape.

The Dutch Navy was much better prepared to fight the Second Anglo-Dutch War (1665-1667). By then it had launched much larger ships, though the largest still had just 70 guns. The Dutch also put to sea with many more professional officers and had adopted improved tactics: the Dutch Navy first fought in line of battle at The Downs (June 1-4/11-14, 1666). But the English had been busy building battleships, too. Their new designs mounted more and heavier guns than the largest Dutch warships. In April 1665 the English had eight First-Rates of 70 guns or more, where the Dutch had just four, and the largest English battleships had 90 and 100 guns. Moreover, Dutch crews were rife with political tension, with some refusing to sail or fight under certain officers or certain colors (that is, the State’s flag vs. the dynastic banner of the Prince of Orange). The Dutch Navy subsequently fought many worthy battles and escorted numerous convoys to and from the Baltic and Mediterranean. It was fully engaged against the English for a third time during the Third Anglo-Dutch War (1672-1674). Thereafter, the Dutch were more concerned with fighting the French Navy during a series of minor and major wars: the War of Devolution (1667-1668), the Dutch War (1672-1678), the Nine Years’ War (1688-1697), and finally the War of the Spanish Succession (1701-1714). The last two conflicts were fought in alliance with the old foe of Dutch commercial and naval power, the Royal Navy.

Fast craft between the wars

Q 20636

The British hard-chined Coastal Motor Boats of World War I were very fast but required constant attention to trim in order to get the best performance. 1919 saw them in use in a little-known campaign on the Caspian, during the intervention by the Western powers in Russia.


S12 and S13 were part of the first batch of German motor torpedo boats, completed in I 934. Displacing 78 tons, they were 32.3-m (l 06-ft) boats armed with two 533-mm (21-in) torpedoes and a single 20-mm (0.78-in)gun intended for an AA role.



Fast coastal craft proved their worth during World War I, with the Italians achieving the greatest successes, including the sinking of several battleships. In the inter-war years the larger fleets concentrated on major units and ignored coastal craft, but Germany and Italy continued their development, giving them a substantial lead by 1939.

Although the development of the automotive torpedo in the late 19th century promised to realize the dream of the small warship with the killer punch, the need for this ‘torpedo boat’ to work with and against fleets at sea stimulated too large an increase in size, a trend aggravated by the contemporary technology of steam machinery in displacement hulls. The development of the fast planing hull and the internal combustion engine began the cycle afresh, with progress before 1914 owing much to the commercial prospects of high-speed boating. It was but a small step to mount torpedoes on such craft, and the same specialist yards have tended to remain in the business to this day.

Much effort was put into the production of torpedo-carrying coastal craft during World War l, but only the Italians in the Adriatic and the British in the English Channel and the Baltic ever demonstrated their true potential. Neither employed massed attack, preferring to work singly or in small groups to capitalize on the advantages of agility, surprise and good planning. The Italians were particularly imaginative, evolving craft and tactics to assault an Austro-Hungarian fleet snug in well-defended harbours. The British had to contend with poorer weather conditions and soon learned the value of larger and stronger hulls. They also discovered the threat posed by aircraft and fire from ashore, suffering losses from both despite small size and manoeuvrability. Experience did not turn the British away from hard-chine designs; they accepted a drop in performance in heavy weather in exchange for the benefit of really high speed in calmer water.

After World War I the British totally lost interest in coastal craft, being occupied with deep-sea imperial matters. The Italians went on initially to be joint front runners with the Germans, who saw in the small-torpedo boat a means of constructing useful naval tonnage outside treaty restrictions. Beneath the lax gaze of the regulating authorities they built and evaluated numerous hulls under sporting-club colours and, over a decade, identified what were to be the major S-boat characteristics: displacement hull, wood on light alloy construction, stability reserves for 533-mm (21-in) torpedoes and, finally, the small marine diesel. This type of engine required careful development and, once perfected, remained peculiar to German practice, with foreign navies never producing a satisfactory competitor despite the fire risks associated with petrol engines, for which they treated effect rather than cause by introducing self-sealing tanks and improved fire-extinguishing systems.

The Italian lsotta-Fraschini was an excellent petrol engine, used widely abroad until 1940; it was probably its very availability that inhibited comparable development elsewhere. During World War I the Italians found the small planing hull adequate for their Adriatic operations. Translated into the open-sea war of 1940-3 it proved unsatisfactory and was dropped in favour of a German type of round-bilge form.

A considerable increase in efficiency resulted in the abandoning of direct-drive for purpose-designed reduction gearboxes and propellers, though transmission problems and structural failures proliferated with small hulls that ‘worked’ in a seaway. Wood had the necessary resilience and ease of repair where clad on timber or light alloy frames. All-aluminium alloy hulls corroded disastrous salt-water conditions. As in the pre-transitional navy, it was found that wooden hulls could not exceed a certain length and, for instance in the British SGBs steel had to be used. A great British innovation was to abandon traditional boat-building methods for mass production, using prefabricated techniques. Once certain weaknesses had been rectified, this system realized greater numbers of craft.

Hard-used fast coastal craft have a short operational life and demand continual attention. Specialized depot ships, or tenders, enabled squadrons to operate successfully ‘up-front’. The Americans particularly made great use of them, offering off duty crews accommodation and facilities while undertaking endless hull and machinery repairs, and servicing armament.

It had been assumed between the wars that coastal craft would be needed in inshore ASW role, a belief that hung on until the British SDBs of the 1950s. In the event, submarines generally operated further offshore and those which were destroyed by small craft were despatched by torpedo while navigating on the surface. Specialist AS boats were, therefore, rapidly re-armed as gunboats, their depth charges removed. It remained the practice, however, for many boats to retain a pair of charges for the deterrence of close pursuit.

Small torpedoes of up to 457-mm (18-in) calibre proved to have insufficient ship-stopping capacity, but the size and weight of two or four 533-mm (21-in) weapons tended to dictate the parameters of the boats themselves, to the extent that the Americans developed a special ‘short’ version. To save the weight of tubes, dropping gear was introduced, though this left the torpedoes themselves vulnerable to damage. The Germans preferred to retain their two enclosed tubes forward, with a reload for each stowed safely behind a bulwark.

Close-in fighting was typically brief and bloody, involving large volumes of volumes from light automatic weapons. Armour was gradually introduced as a result the Germans going as far as an armoured wheelhouse. Initially the British were at a disadvantage with only machine-guns to match the German 20-mm cannon, whose explosive or incendiary shells were lethal to wooden hulls loaded with petrol and ammunition.

As ever, armament developed to suit the need. American PT boats, involved in the Far East against the eternal and apparently unstoppable Japanese barge traffic, shed some or all of their torpedoes in favour of weapons such as racked 127-mm (5-in) rockets and 81-mm (3.2-in) mortars. British boats faced similar problems with the German MFPs, or ‘F’ lighters, in such areas as the Aegean and Adriatic. Like the Japanese, these craft were of a draught too shallow to be vulnerable torpedoes and could take aboard a variable armament which often included much-respected 88–mm (3.46-mm) gun. British MGBs responded appropriately, toting guns as large as the short-barrelled 114-mm (4.5-in) gun.

Radar, available to small craft, was a boon in the vicious nocturnal encounters where opponents could usually be seen only fleetingly and for very short periods. Paradoxically, it was radar-controlled gunfire on the part of larger ships that offset the torpedo boat’s advantages by effectively outranging its main weapon.

Come the peace there was no sentiment, the boats being deleted in hundreds destroyed by burning and many surviving a swords-to-ploughshares transfiguration to become houseboats of surprising durability.

Interest in small craft lapsed again on the part of the larger navies until that day in 1967 when the Eilat became the first major SSM casualty.

Dreadnoughts’ three




All-big-gun designs commenced almost simultaneously in three navies. The Imperial Japanese Navy authorized the construction of Satsuma, designed with twelve 12-inch (305 mm) guns in 1904; she was laid down in May. The Royal Navy began the design of HMS Dreadnought in January 1905; she was laid down in October. The U.S. Navy gained authorization for USS Michigan, carrying eight 12-inch guns in March; she was laid down in December 1906.

The move to all-big-gun designs was accomplished because a uniform, heavy-caliber armament offered advantages in both firepower and fire control, and the Russo-Japanese War showed that naval battles could, and likely would, be fought at long distances. The newest 12-inch (305 mm) guns had more long-range firepower than a gun of 10-inch (254 mm) or 9.2-inch (234 mm) caliber. Most historians also cite advantages in fire control; at long ranges guns were aimed by observing the splashes caused by shells fired in salvos, and it was difficult to interpret different splashes caused by different calibers of gun. There is still debate as to whether this point was important.

The Royal Navy had to accelerate Dreadnought’s construction, knowing full well that the other major naval powers had their own dreadnought-type battleships on the drawing boards. In fact, the Japanese Satsuma class (laid down in 1903, completed in 1909) should be credited as the world’s first all-big gun battleships laid down. Plans for the U. S. Navy’s dreadnought-type battleships, the South Carolina class (laid down in 1905, completed in 1910) had also been drawn up before Dreadnought. The naval powers had come to realize that smaller-caliber guns on battleships led to confusion in gunnery spotting during battle, that mixed-caliber projectiles complicated handling, and that a single heavy gun size would simplify matters across the board. In sum, Dreadnought set the pattern for the 177 dreadnought-type warships subsequently laid down by the world’s navies between 1905 and 1941 (this figure includes uncompleted battleships).

Dreadnought embodied several significant technological advantages already enjoyed by the Royal Navy. The first was its heavy 12-inch and later 13.5-inch and 15-inch guns, with their greater hitting power and their flatter trajectories-that is, when their shells performed as designed. The second was Dreadnought’s faster turn of speed.

The greatest single undisputed Royal Navy superiority lay in its dreadnoughts’ turbines, pioneered by Dreadnought itself. At the time, no large steam turbine-powered ship had even been laid down, and the first RN turbine-propelled destroyers had been at sea only for four years. Turbines, lighter and more compact than reciprocating engines, gave Dreadnought a 2-knot advantage over its closest contemporaries; they were also more durable. Great Britain was so far ahead in turbine manufacturing, in fact, that for years afterward even advanced maritime powers such as the United States, Italy, Japan, and Germany had to build turbines under licenses from British firms. The United States did not go over to its own domestic turbines (Curtis) until the Nevadas (laid down in 1912). The Italians installed the Parsons turbine drive for their first dreadnought (Dante Alighieri, laid down in 1909) and did not install a domestically manufactured turbine (from Bulluzo) until the Littorio class (laid down in 1934-1938). The French stuck with Parsons turbines (with one mixed-drive exception) through to the end of their battleship construction. The first German turbine-powered battleships, the Kaiser class, were not even laid down until almost five years after Dreadnought. (This fact alone should invalidate much of the popular assertions of German technological superiority, spread as much by British journalists as by the Germans.)

The U. S. Navy, full of imperial visions in the wake of the triumphant Spanish-American War, had every expectation of soon surpassing the size and strength of the Royal Navy. As it was, the U. S. Navy trumped Dreadnought with its new South Carolina class (South Carolina and Michigan, completed in 1910) by arranging all of their heavy guns line-ahead, one turret mounted over another, a design pattern that all dreadnoughts would follow. The British and the Germans persisted in mounting wing turrets until the former’s Orions, laid down in 1909, and the latter’s Koenigs, laid down in 1911. But the U. S. designers hesitated to install turbines, so the South Carolinas had a speed some three knots slower than Dreadnought. The South Carolinas thus were not deployed to European waters during World War I and, in some circles, were not even considered to be dreadnoughts. At any rate, the Americans built their battleships for long range and protection, sacrificing some speed in the process.


The Steam Powered Warships

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‘It was at this same (1897 Fleet Review at Spithead) Review that a wonderful little vessel named the “Turbinia” appeared, steaming through the Fleet at 35 knots, a speed never before achieved on water. She was the first ship to be fitted with the turbine machinery invented by her owner, the Hon. C. A. Parsons of Newcastle-on-Tyne, and a great sensation was caused by her steaming through the lines at such a speed. Whilst she was at anchor in Portsmouth Harbour, I went aboard and told the owner that I would like to get a snap of his craft going at full speed.

“No one has succeeded yet, although many have tried”, replied Mr. Parsons.

“I should like to have a shot at her”, I persisted.

“Alright, so you shall!” he said with a smile, “I will make another run through the fleet tomorrow, look out for me between lines A. and B. at noon. That should give you an opportunity.”

“I’ll be there, opposite the Flagship”, I told him,

Punctually at l2 o’clock there appeared between the leaders of the lines a smother of foam – it was the “Turbinia”. As she raced past the Flagship, I was waiting in my launch and took a flying shot of her. When I developed the plate I was delighted to find that I had “got her”, and the owner was so pleased with the result that he invited me to take a number of photographs and a cinematograph film of his craft on the Tyne.’


For thousands of years, most mariners had dreamed of being able to take a large cargo anywhere they wanted without worrying about wind and currents. High-ranking British naval officers in the 19th century were the exception. We’ll come to that in a moment.

Ships propelled by oars could, of course, proceed into the wind (although progress was a lot slower than if there were no wind), but the large number of rowers precluded carrying much cargo and ensured that such ships as the Greek triremes (a galley with three banks of rowers) could not go far from land. Primitive sails like those of the classical galleys or the Arab dhows could take a vessel a long distance if the wind were favorable, but not if it were in the wrong direction. That’s why a dhow plying the Indian Ocean trade took a year to make a round trip. Half of the year the winds blew to the West; the other half, to the East. Scandinavian seamen learned to manipulate a square sail to allow some progress against the wind, as did Arab sailors using the lateen sail. But even after Europeans developed the full-rigged ship, progress could be slow unless the weather cooperated. If there was no wind, progress was nil.

The steam engine changed sailing radically, and that transformed warfare at sea. But the steam engine would not have been possible without a previous advance in the art of war. In the 18th century, a Swiss gunfounder named Jean Maritz, improved the rough, sometimes-crooked bores of cannons by inventing a machine for boring out the barrel after the gun was cast solid, instead of incorporating the bore in the casting. A few years later, in 1774, a British engineer named John Wilkinson improved the machine. Wilkinson’s device created an extremely smooth and precise hole. With a machine like that, the pioneers of steam power were able to build cylinders with tight-fitting, efficient pistons. Such cylinder and piston arrangements are essential to early steam engines as well as modern internal combustion engines.

The first steam engines worked by filling a cylinder with steam, then condensing it to water. The vacuum created drew the piston into the cylinder. These “atmospheric” engines were useful for pumping out mines and other tasks where their weight was not important. They were far too heavy and bulky to use aboard ships, however. James Watts’s improved steam engine drove the piston in the opposite direction—expanding steam, rather than atmospheric pressure on a vacuum was the driving force. Such engines could be made small enough to power a ship. Their earliest use was to turn a pair of huge side wheels.

Steam gave navies a great strategic advantage. Steam warships no longer depended on weather and could cross the oceans much faster than sailing ships. “Seizing the weather gauge” (maneuvering into the best location to take advantage of the wind) had long been a favorite tactic of British seamen. It no longer gave any advantage. For that reason, Britain, although it was the home of the first steam engines and it utterly depended on its navy for its primacy in world affairs, tried to retard the development of steam-powered ships. British naval personnel were the most skilled in the world; British shipyards devoted to building sailing men-of-war were the biggest in the world; British technology in preserving food for long journeys, manufacturing the heavy, short-range cannons, called carronades, and everything else needed for wooden, sail-driven warships, led the world. If the world’s navies went to steam, all of that would be worthless.

In 1828, the British admiralty expressed their views on steam-powered warships:

Their lordships feel it is their bounden duty to discourage to the utmost of their ability the employment of steam vessels, as they consider that the introduction of steam is calculated to strike a fatal blow at the naval supremacy of the Empire.

In spite of the size of the British Navy, this policy bore more than a little resemblance to the actions of an earlier British authority figure: King Canute, who tried to tell the tide to reverse itself. The American, Robert Fulton, had built a working steam ship as early as 1807. In 1837, the paddle wheel steamer Sirius crossed the Atlantic in 18 days—breathtaking speed in an era when Atlantic crossings were measured in months.

Although the new method of propulsion had manifest advantages, the world’s navies did not immediately board the steamship. The French started building steam warships in the 1840s, but they did so on a small scale. There were a number of reasons for this slow progress. There was the natural conservatism of sailors and military men, and that the British, owners of the world’s most powerful navy, professed to see little value in the new technology. And, most important, there was the fact that the early steamships could not survive a battle with sailing warships of comparable size. The huge paddle wheels on each side of the vessel were vulnerable to gunfire, and they made it impossible for the ship to carry enough cannons along the side to match the broadsides of a sailing ship. Another drawback was that steamships could not stay at sea nearly indefinitely, as the sailing ships could. They had to be near a supply of coal.

The paddle wheel was the first drawback eliminated. In its place, ship builders used the screw propeller. The new device had to rotate much faster than a paddle wheel, which meant both major changes in gearing and much more efficient engines. John Ericsson, a Swedish engineer, invented both a screw propeller that worked and an engine to drive it. He sold the designs to the U.S. Navy, and in 1842 the U.S.S. Princeton became the world’s first screw-propelled steamship. Princeton’s engine and drive shaft were located below the waterline for protection, and the ship was able to carry enough guns for a broadside. In 1843, the British steamer Great Britain became the first screw-equipped ship to cross the Atlantic.

The age of steam had arrived. Ship builders were still hedging their bets by equipping their vessels with masts and rigging that could be used if the engine failed, but it was hard to navigate a paddle wheeler using sails alone. Screw propellers made sailing easier, but even the propeller caused interference. The next major improvement in warships was adding armor. Another huge advance in steam engines after the introduction of armor was the steam turbine engine, which used a spinning wheel turned by rapidly expanding steam to propel the vessel. These engines made possible the high-speed torpedo boats that threatened the supremacy of the battleship at the turn of the 19th and 20th centuries. At the British Jubilee Naval Review in 1897, the steam launch Turbinia stole the show as it dashed in and out of the line of battleships at the unheard-of speed of 34 1/2 knots.

Allied Countermeasures against the snorkel-equipped U-boat I

The Illustrated London News, 23 December 1944. Prime Minister Winston Churchill and President Franklin D Roosevelt jointly announced to the public on 9 December that German U-boats were now equipped with a device that allowed them to remain submerged. Five days later First Lord of the Admiralty A V Alexander followed up with a public warning that with the appearance of this new device heavy losses should be expected by the public. The day after this illustration was published the snorkel and Alberich-equipped U-486 (VIIC) sunk the SS Leopoldville outside Cherbourg Harbour despite it having a Royal Navy escort, causing a significant loss of life among the US 66th Infantry Division being sent as reinforcements to the Western Front.

The snorkel was treated as a ‘secret’ development by the Kriegsmarine when it was introduced. Allied intelligence certainly intercepted wireless traffic about its existence through Ultra intercepts. However, it appears that the best information came from captured German crewmen picked up after their U-boat was sunk or scuttled.

The British Admiralty’s Naval Intelligence Division’s C.B. 04051 (103) Interrogation of U-Boat Survivors, Cumulative Edition, June 1944 was the first known assessment of the German snorkel. The document revealed that the equipment as well as its basic technical schematics were known to the British at the very start of the Normandy invasion. While this document was descriptive, it did not contain any analysis of the snorkel’s operational or tactical potential as U-boat tactics had not yet evolved. Consequently, the report did not assess any impacts to ongoing Royal Navy Escort or Support Group tactical responses during a U-boat hunt.

This information acquired by British intelligence was accurate. It is clear that by June they had gained knowledge of the Type II non-flange mast as well as the replacement of the pulley system with a hydraulic piston lift. Both design improvements were starting to be fielded broadly across the U-boat fleet, as in the case of U-480, which received a second snorkel installation that summer, upgrading from the Type I to the Type II. The Admiralty report understood that the snorkel was intended for charging, but clearly did not opine the consequences of a non-existent U-boat profile on their detection gear, or the possibility that U-boats could remain submerged for almost their entire patrol. In November British forces that occupied the former German U-boat base at Salamis, Greece, found technical renderings of the Type II snorkel mast installation for Type VIICs, the first such technical documents of their kind obtained by Allied intelligence.

Four months later, US Naval Intelligence observed the stark drop off of actionable intelligence, defined by immediate, readable Ultra intercepts or HF/DF map plots that allowed them to ‘fix’ a U-boat’s location. The report noted the decrease in wireless transmissions and change in Enigma keys, as well as the atmospheric conditions that impacted reception in the North Atlantic. These observations prompted OP-20-G to publish a memorandum notifying US Naval leadership about the impact of these developments to anti-U-boat operations. What the report did not mention was the fact that a number of the intelligence impacts were caused by the introduction of the snorkel, suggesting that OP-20-G did not fully comprehend the correlation. A contributing factor to the lack of understanding was that most snorkel-fitted U-boats were being employed almost exclusively around the coastal regions of the British Isles and not in the convoy lanes of the North Atlantic.

A few statements of note in the 24 November 1944 report are of interest. ‘The problem of fixing U-boats in the Atlantic has become more difficult and will probably continue so …’ for the following reasons: ‘Approximately 90% of the D/F cases have involved U-boat transmissions of the ration of 30 seconds or less. Such short transmissions make it difficult to obtain any large number of high quality bearings.’; ‘the use of Norddeich Off Frequencies has become more general for all types of transmissions. It has been our experience that fewer bearings are obtained on all frequency transmissions of short or medium duration, thereby resulting in less accurate fixes’; ‘U-boats have been maintaining a rigid condition of radio silence. We have noted U-boats on patrol in various areas in the North Atlantic for periods as long as 30 or 40 days without making a single radio transmission’; and ‘ionospheric disturbances, in the North Atlantic in the winter have a detrimental effect upon D/F fixing’.

This resulted in the conclusion by OP-20-G that ‘the accurate locating of U-boats by means of Ultra information has progressively become more and more difficult’.

The OP-20-G memorandum balanced the fact that the dramatic reduction in reliable U-boat position signals was assessed as not impacting operations too significantly given the fact that few U-boats were operating in the mid-Atlantic. The report assumed that if traditional Wolfpack tactics were reinstituted in the spring of 1945 then a natural increase of signals would result in a resumption of accurate U-boat position information. Like the Admiralty report of June, this US Navy intelligence assessment failed to appreciate the paradigm shift introduced by the snorkel.

Overnight the snorkel rendered Allied radar detection almost ineffective and significantly reduced the value of Ultra in fixing U-boats for hunter-killer groups. Yet, a review of US and British intelligence reports revealed that it took both countries about six months to appreciate the snorkel’s impact on their anti-U-boat operations and implement effective countermeasures.

This was revealed by Ladislas Farago, who served as the Chief of Research and Planning in the US Navy’s Special Warfare Branch (OP-16-Z) during the Second World War. Writing after the war, he offered how unprepared the Western Allies were in the face of snorkel-equipped U-boats. The US Tenth Fleet was organised in May 1943 at the very height of the North Atlantic convoy battles as the first anti-submarine command. Its mission was to find, fix, and destroy German U-boats. To this end, its supporting missions included the protection of coastal merchant shipping, the centralisation of control and routing of convoys, and the co-ordination and supervision of all US Navy anti-submarine warfare training, anti-submarine intelligence, and co-ordination with the Allied nations. The Tenth Fleet had no organic naval vessels. Its commander, Admiral Ernest King, used Commander-in-Chief Atlantic’s (CINCLANT) vessels operationally, and CINCLANT issued operational orders to escort groups originating in the United States. The Tenth Fleet was also responsible for the organisation and operational control of hunter-killer groups in the Atlantic.

The Tenth Fleet was ‘misled in its appreciation of the snorkel by reports that tended to emphasise the deficiencies of the device’, according to Farago. Interrogations of German U-boat prisoners early in 1944 who had participated in the first snorkel trials and training in the Baltic spoke despairingly of the device. At this time no U-boat had conducted an operational cruise and not even the German U-boat command understood the device’s full potential. OP-16-Z produced a number of intelligence broadcasts that disparaged the device through the Tenth Fleet. By the summer of 1944 the Tenth Fleet dismissed the snorkel as a viable technological solution for the U-boat. This assessment changed by the late summer and early autumn of 1944 with the approach of U-518 (IXC) off North Carolina in August, followed by others off Canada (see Chapter 9). U-518 sank the SS George Ade, 100 miles from the US East Coast – the first American-flagged ship sunk by a snorkel-equipped U-boat. All Tenth Fleet efforts to hunt down this U-boat failed, leaving it concerned.

The Allies had no tactics or technology to counter the new threat, which was the responsibility of the US Navy’s Tenth Fleet. Farago noted in the early 1960s:

In a very real sense, then, the snorkel thus succeeded in doing exactly what Doenitz hoped it would accomplish: it provided effective protection from the U-boats’ most dangerous foe, the planes of the escort carrier groups. The protection was so effective, indeed, that from September, 1944, through March, 1945, the escort carrier groups managed to sink but a single U-boat, and a non-snorkeller at that, although they accounted for forty-six U-boats during the prior sixteen months.

The Allies devised a simple division of labour in terms of counter-U-boat operations from 1942 onward. The US Navy’s hunter-killer groups were given the responsibility for the central Atlantic and US East Coast, while the British and Canadian air and surface forces were responsible for their respective coastal regions as well as the North Atlantic. This generally placed the burden of counter-U-boat operations on the US Navy from 1942 until early 1944, when U-boats were non-snorkel equipped and operated in Wolfpacks. Once the snorkel was introduced the burden of anti-U-boat operations shifted to the British and Canadian forces through to the end of the war. This included the development of new tactics. It is made clear in reviewing available primary documents that by the end of the war the British and Canadian Royal Navies appreciated the fact that they were fighting a very different U-boat foe, and adapted accordingly. The US Navy and US Coast Guard, however, did not have that same appreciation due to a lack of operational experience against snorkel-equipped U-boats.

Allied Air Operations

In order to destroy a U-boat, it had to be located. By the spring of 1944 location and destruction was predominately carried out by radar-equipped Allied aircraft. The British Air Ministry published ORS/CC Report Nr. 325 on 5 January 1945 titled Operational Experience Against U-Boats Fitted with Snorkel, which summarised the negative impact the snorkel had on Allied air operations against U-boats during the previous six months. The report began: ‘Throughout the past few months the German U-boat fleet have been fitted with a “Snorkel” pipe, about 16’ in diameter and showing some 2–3 feet above the water, through which the air for the Diesels can be sucked in and the exhaust expelled. The consistent use of this device has very considerably reduced the efficiency of [aircraft] detection of U-boats – probably by a factor of about 10, and produced a return to close-in submarine warfare.’

Based on past operational results the following ‘recommendations and statements of fact are considered to follow fairly definitely from the scanty data on operations:’

1. Snorkels are usually seen by their wake and ‘smoke’, this ‘smoke’ is however only produced on some occasions, much more frequent in winter. Theoretical investigation in progress may enable this effect to be predicted. The average citing ranges are average ‘smoke’ 7 miles, (two cases of 20 miles!), wake 4½ miles, snorkel itself about 1 mile.

2. An improvement in efficiency of two- or three-fold could be obtained by use of binoculars throughout.

3. Very little use has in fact been made of binoculars, even for recognition.

4. The operational range of detection on a ASV Mark V (4 miles) is about one third of the operational range on surfaced boats (13 miles), but

5. Radar efficiency is very low and sees more than Force 3 – because of the sea returns.

6. The proportion of snorkel U-boats seen snorkelling and subsequently attacked while visible, or less than 15 seconds dived, amounts to 70% of attacks.

7. Hence the depth charge setting for snorkels should be that proper to ‘snorkel depth’ itself.

8. The sighting range in Leigh-Lights at night is so low (about 400 yards media) that visual bombing holds out little hope. Radar bombing and or homing weapons will be essential.

It was noted in the study that U-boats could clearly be identified through the wakes left by the periscope or snorkel. In the last several months snorkels could be identified seven times greater through the ‘smoke’ trail. This ‘smoke’ was probably vapour caused by a snorkel riding too high out of the water, exposing its exhaust vent. However, the British assessment identified that the smoke, which was usually described as grey in colour, was ‘presumably largely water mist that became clearly visible and much more frequent in cold weather’. The results up to November, according to the assessment, ‘show so low a proportion of ‘smoking snorkels’ (9 out of 22 = 40 per cent) that this phenomenon must be due to some special weather conditions, more frequent in winter than summer’. It was made apparent by the study that the British pilots were not utilising binoculars during their air patrols and that a periscope or snorkel that was not smoking could be identified by binoculars at about 4.5-mile range, while the naked eye could only identify it at a range of 1.9 miles. Despite this fact, the study stated that very few periscopes or snorkels were in fact either first sighted or even recognised using binoculars. Even when air patrols used binoculars, they assessed that periscopes were identified only 16 per cent of the time, while snorkels only 33 per cent. By binocular ‘recognition’ it was meant ‘to identify the vague phenomenon: wakes, smoke, odd looking waves, etc. which are usually first seen’. The study also looked at the rate at which binoculars could identify a periscope or snorkel when radar contact had provided a rough bearing an exact range. It was determined that a binocular was used to confirm a radar bearing 19 per cent of the time. All this led to the conclusion that ‘there is room for considerable improvement in the use of binoculars, both regular scanning by lookouts detailed for the purpose whenever the neck disability is more than 5 miles and for recognition of radar blips. The second point could be met by the second pilots always keeping a pair of binoculars ready focused.’ What this assessment did not consider was the fact that U-boats predominately snorkelled at night as directed by BdU [Befehlshaber der Unterseeboote], limiting the effectiveness of visual identification even further.

A separate detailed analysis was conducted on daylight attacks against U-boats by aircraft during the period June to December 1944. This study focused on U-boats that submerged once they were attacked on the surface. The report was divided into attacks that occurred when a U-boat had been submerged for less than fifteen seconds, submerged between fifteen and sixty seconds, submerged more than sixty seconds, and were lost while the aircraft was manoeuvring to attack. The study found that whether the U-boat was identified operating with just a periscope or snorkel separately, or the U-boat was identified operating both simultaneously, it was impossible to obtain a kill once the vessel began to submerge. The kill rate per attack when the snorkel and/or periscope were still visible was only at 17 per cent. This was 50 per cent less than the 43 per cent kill rate for a completely surfaced U-boat. The study went on to state ‘the number of snorkel sightings leading to targets visible, partly visible or dived less than 15 seconds (41% of sightings, 74% of attacks) is so high that the DC’s against snorkels should have the depth setting proper to the boat actually snorkelling’. This data does support that the U-boat dipole mounted on the snorkel mast was effective in identifying attacking aircraft, giving U-boats the advantage of diving before an air attack commenced. A fifteen-second advantage was enough to gain survivability against an air attack regardless of how far out the aircraft identified the snorkelling U-boat. The realisation that snorkel ‘smoke’ was a marked advantage caused British Coastal Command to issue a memo that declared this study was only permitted to be circulated among those engaged in ‘Air Anti-U-boat Warfare’. Not even the Royal Navy was notified of this observation in order to maintain strict secrecy over this operational advantage. Given that this memo was issued on 22 March 1945, at the end of winter, it probably contributed little to the anti-U-boat effort. However, it does show how seriously the snorkel altered the balance sheet against Allied aircraft.

One effective Allied aircraft tactic against snorkel-equipped U-boats introduced was the use of sonobuoys. U-boat commanders noted in their short reports to BdU that Allied aircraft dropped sonobuoys in areas where their snorkels were presumably seen to alert other aircraft or anti-submarine groups to the U-boat’s diving points. All U-boats were warned of this tactic on 15 February by BdU, suggesting it was a recently employed tactic. There were two types of sonobuoys, one for listening and one for HF/DF. The HF/DF buoy was less effective as snorkel-equipped U-boats rarely transmitted wireless signals. It was the direction-finding buoy that was used with effect during the last six months of the war against the snorkel-equipped U-boat.

Sonobuoys were originally intended to be dropped manually from blimps. Parachutes were added when the decision to deploy them from manoeuvring aircraft was made. They were equipped with a stored, self-erecting antenna. The first operational passive broadband sonobuoy was known as AN/CRT-1. The operational frequency of the AN/CRT-1 was 300Hz to 8kHz, which was within the audible range of the human ear. The operator had to make real-time decisions based on his ability to distinguish various underwater sounds. The problem was that in shallow water the operator had to contend with a host of other noises caused by waves, currents and density layers, making identification of a U-boat operating on electric motors or even drifting with engines off problematic. An improved version, the AN/CRT-1A, also known as the Expendable Radio Sonobuoy (ERSB), had an increased frequency band of 100Hz to 10 kHz and lighter weight (12.7lb).

The improved sonobuoy contained enough battery power for four hours of continuous operation. It was not until June 1944 that these new sonobuoys were being employed by US aircraft squadrons operating in the central Atlantic. It was not until the autumn of 1944 that a single British aircraft squadron received the device for employment.

As an approximation, an aircraft equipped with eight sonobuoys could hold contact with a U-boat for sixty to ninety minutes, and if equipped with twelve, for as long as three hours. This was ample time to vector in a surface hunter-killer group or squadron. The drawback was that calm water was required to achieve these contact times.

The British also took a careful look at operational and practice data recording radar returns against the snorkel. The data the British collected was identified by their own intelligence analysts as ‘scanty’. The S-Band equipment, while operational, could not be compared effectively with the X-Band, which was not yet operational. However, in looking at the MK.V Liberator it was noted that the operational range to identify a periscope or snorkel was 4.7 miles compared with the average of 12.9 miles by day or 14.3 miles by night for this specific equipment on surfaced U-boats. It was thought that the ratio of a third would appear promising until it was realised that this fact implied the majority of these contacts would appear inside the ‘sea returns’ and thus be almost impossible to recognise by sight. The study predicted that in a calm sea the MK.V Liberator had a ratio of 10:1 to identify the snorkel or periscope, while the MK.III Wellington’s ratio was 6:1. In moderate seas the ratios were respectively 50:1 and 30:1. In rough seas it was considered next to impossible to make a radar contact. The conclusion was that the S-Band’s operational range against snorkels ‘appears to be about one-third of that on surfaced U-boats’. In addition ‘detection of snorkel radar in seas of Force 3 or higher is much more difficult than in calmer seas’.

While the above data was based on daylight attacks, a sobering assessment of night-time attacks was also made. The study concluded: ‘The sighting range of the snorkel at night is so low that the technique of attack hitherto used, i.e. radar contact – visual sighting – release of bombs by visual judgment – holds out little hope of success. It is suggested that either radar bomb sites or homing weapons or both are essential.’ This observation is interesting when compared with the procedures outlined to German U-boats by BdU that snorkelling should be carried out at night. This meant that if proper guidance was followed then a snorkel-equipped U-boat’s survivability against aerial identification and attack was very high. No calculations were made by the British in their report between snorkels camouflaged with anti-radar matting and those without. The process of covering snorkel masts with the Wesch anti-radar matting became commonplace in the autumn of 1944 and served to reduce the ability of Allied radar detection even further than already indicated in the above assessment.

The British knew the U-boats were there but were now unable to easily locate them or even effectively employ their aircraft and radar technology against them. The study noted that ‘of the conclusions drawn some are practically certain; others are open to some doubt as based on small numbers. It is however, considered that, in view of the urgency of the snorkel problem, these probable conclusions should also be drawn.’ Indeed, there was a snorkel problem. Six months into this problem the Western Allies were still struggling to identify probable countermeasures against an enemy that they thought was defeated in May 1943, but that had now returned with a vengeance.

Given the negative impact that the snorkel had on British air-based antisubmarine efforts, a series of meetings were convened starting on 22 November 1944 that were intended to address the issue. Meetings followed on 15 December, 19 January 1945, 29 January and 13 March to identify solutions to the troubling snorkel trend. These meetings were held in Room 71/II at Whitehall in the Air Ministry and were chaired by Sir Robert Renwick Bt, who looked for updates from Air Commodore H Leedham, CB, OBE, as the DCD (Director of Communications Development), and Dr A C B Lovell, as the TRE, on ‘actions taken by the DCD and TRE (Telecommunications Research Establishment) to provide anti-Schnorkel measures …’ In the first meeting in November it was stated that ‘methods that could be introduced into existing equipment which it was anticipated would give some 20%–25% increase in the ratio of the snorkel responses as against those of sea returns’. In addition, Commodore Leedham believed that either X-Band or K-Band could be used but at least another month of experiments was required. It was confirmed in December that ongoing trials suggested that modifications to both the Wellington and Warwick systems would allow them to better pick up smaller targets. X-Band trials were still ongoing. It was also recommended that American detection systems be included in the testing programme.

In the 19 January meeting it was expressed that significant delays caused by wrongly specified equipment had prevented Coastal Command from equipping their aircraft with the new detection system modifications. K-Band was given the highest priority and X-Band results were promising. By 29 January, Coastal Command aircraft were finally receiving modifications to their radar sets that would allow for better detection of smaller targets. Interestingly, it was noted that the tests being performed off Llandudno, North Wales, in the Irish Sea against British submarine test targets had to stop due to the presence of actual U-boats in the testing area. The first X-Band-equipped Warwick Mk V aircraft were expected to be delivered in late March or early April.

The Air Ministry wanted to increase their chances of a successful attack against a snorkel-equipped U-boat by 20 per cent. Most of their recommendations, however, were not implemented until the spring of 1945. The US was not involved in these meetings, primarily as they were not directly engaged in the snorkel war to any great extent. British findings were to be made available to the US primarily because it was thought they would ‘interest them’.

BdU issued new guidance on 3 March 1945 to their U-boats based on changes introduced by British Coastal Command air patrols. Specifically, Message No. 226C reminded U-boats to maintain depth discipline when snorkelling and avoid being observed. Seven days later, on 10 March 1945, a follow-on message was sent, followed by further guidance to maintain a low snorkel profile in calm surface conditions embodied in Message No. 228B.

What BdU did not calculate was that with the coming of spring, North Atlantic storms gave way to calmer water, as noted by the reference in Message No. 228B of a sea state 1. This increased the potential of a U-boat’s identification through a raised snorkel or periscope by Allied radar or visual recognition.