German concern over Turkish powers of resistance led to the decision to send German submarines to the Mediterranean. The results were actually even more damaging for the Anglo-French cause than the failure of the Dardanelles campaign. In early March, as the British and French warships pounded away at the Dardanelles, Enver Pasha and the Turkish leaders pleaded for submarines to attack the Allied fleet. The Germans tried to induce their Austrian allies to send a submarine out from the Adriatic to the Dardanelles. The Austrians declined, largely for technical reasons. They had only seven submarines, and most of them lacked the range. Moreover, with their former Triple Alliance ally Italy drifting into a position of open hostility, they were obviously loath to lose the services of any of their handful of underseas craft, which had so far proved so effective in restricting the operations of the overwhelmingly superior French fleet. The Germans eventually despaired of getting anything from the Austrians and resolved to do the job themselves. On 13 March they decided to send one large boat with extra fuel oil directly to the Mediterranean, while a pair of small UB.I-class boats would be sent in sections by rail to Pola, where they would be assembled by German engineers. They anticipated the UB boats would arrive in Turkish waters about the end of April.
A major problem for the British and French was therefore on the way, but it would have no effect on their landings on the peninsula, which took place on 25 April. The British 29th Division landed at the tip of Cape Helles, and the Australian and New Zealand Army Corps—the ANZACs—landed farther to the north on the Gallipoli Peninsula and at great cost established a beachhead. The French landed on the Asiatic shore as a diversion, and later shifted their forces to the European side. The Turkish counterattacks failed to push the Allies into the sea, but the Allies in turn could not progress far beyond the beachhead nor capture the commanding height of Achi Baba. Barbed wire and machine guns proved as difficult to overcome at Gallipoli as they were on the western front. The result, despite the landing of new British divisions, was a stalemate, and the Royal Navy had the major obligation of supplying the army over open beaches from island bases 50 to 60 miles away, providing artillery support, and the added worry that intelligence indicated German submarines were on their way.42 The logistical aspect should not be underestimated. In September Wemyss wrote that at Mudros harbor there were always between 150 and 170 ships, not counting innumerable small craft.
The supplies of the Turkish army on the peninsula were to a large extent waterborne, and on 10 May de Robeck cabled the Admiralty about the possibility of a renewed naval attack to force the Dardanelles and cut off the supply line. De Robeck himself, apparently, did not believe the presence of the Allied fleet in the Marmara would be decisive and was prodded into sending the cable by his chief of staff, Keyes. According to Keyes, de Robeck realized the importance of a successful attack to the army struggling on shore, but feared for the army’s fate should the attack fail, and declined to take responsibility for running the risk of failure. Keyes told him to place the responsibility for ordering the attack on the government but to make it clear that if ordered, he would be prepared to attempt to force the Strait. Guépratte, although not present at the conference, would have been more than ready to participate.
The cable arrived at a bad time in London, where Churchill was in the midst of the negotiations for the naval convention that would accompany Italy’s entry into the war and knew that German submarines were on their way to the Mediterranean and that the Italians would have to be supported by British ships. He therefore favored a “limited operation” to attempt to sweep the Kephez minefield under the cover of the fleet, compelling the forts to exhaust their ammunition. Fisher, however, was against any attempt to rush the Narrows before the army had occupied the adjacent shores and found even the limited operation excessive. Churchill had to compromise with a very weak telegram to de Robeck on the 13th, instructing him to inform the Admiralty and obtain its approval before taking any decisive step. Fisher, supported by the other sea lords, dispatched an additional cable that effectively killed any idea of a renewed naval offensive. They informed de Robeck, always lukewarm about the whole idea, that the Admiralty thought the moment for an independent naval attempt had passed and would not rise again, and that his role was to support the army. After all these years, the bitterness and disappointment of Keyes can still be felt: “So the great opportunities which had been open to the Fleet since 4th April [when the destroyer minesweepers were ready] were allowed to slip away, and the Allied Army, having suffered 26,000 casualties in its effort to secure the Gallipoli shore, was to continue the struggle, in order that the Fleet might steam by without any undue loss.”
The British suffered a severe loss even before the submarines arrived. The old battleship Goliath had anchored in Morto Bay, an exposed position, where her artillery support to the army had provoked the Germans and Turks. On the night of 12–13 May, Kapitänleutnant Rudolph Firle, a German officer commanding the Turkish destroyer Muavenet, succeeded in torpedoing and sinking the Goliath with heavy loss of life. The loss eventually had important political repercussions in England. Fisher, knowing submarines were on the way, had been very nervous over the superdreadnought Queen Elizabeth at the Dardanelles and anxious to bring her back to the Grand Fleet. He now renewed these demands more vigorously than ever, and he and Churchill decided to replace the Queen Elizabeth with the old battleships Exmouth and Venerable and two monitors with 14-inch guns. Kitchener, however, objected to the effect the Queen Elizabeth’s withdrawal would have on the army’s morale. The next few days brought the Fisher-Churchill disagreement over the Dardanelles to the boiling point when Churchill prepared to send additional reinforcements to the Dardanelles, and on 15 May Fisher resigned. Fisher’s resignation came shortly after a scandal over the shortage of artillery shells in France. The government was in danger of being overturned, and Prime Minister Asquith was forced to form a coalition government with the Conservative opposition on 25 May. Their price for joining the government included the demand that Churchill leave the Admiralty, and he was banished to the meaningless sinecure, the Duchy of Lancaster, from which he would shortly resign in disgust for service with the army in France. Arthur J. Balfour, a former prime minister, became first lord, and Admiral Sir Henry Jackson became First Sea Lord.
Churchill’s departure from office coincided with the arrival of German submarines at the Dardanelles. The small UB.7 and UB.8 were assembled at Pola in the first half of May and towed through the Strait of Otranto at night by Austrian warships in order to conserve fuel. They then slipped the tow and headed for the coast of Asia Minor. The larger U-boat, U.21 under Kapitänleutnant Otto Hersing, sailed for the Mediterranean from German waters on 25 April. Hersing met a chartered Spanish supply ship in the Gulf of Corcubion in northwest Spain on the night of 2 May and took on oil. He discovered, however, that the fuel oil was unsuitable for his diesel engines. Hersing made careful calculations and decided to proceed to Cattaro directly, where by economical use of his engines he arrived on 13 May with only 1.8 tons of his original 56.5 tons of fuel remaining. Hersing proved it was possible for U-boats to make the voyage to the Mediterranean directly from Germany, and in the future newer U-boats would be able to omit the potentially troublesome clandestine call in neutral Spain.
The wireless messages to U.21 at Cattaro were intercepted and read by Room 40, which passed on the warning to de Robeck. De Robeck decided to meet the danger by ordering troop transports to go no farther than Mudros, where troops would be ferried to the Gallipoli Peninsula at night by fleet sweepers. Vital ammunition ships would also discharge their cargoes into trawlers and sweepers at Mudros. Regular supply ships would still go, if necessary, to Cape Helles or Kephalo (Imbros), where advance bases would be created by means of net and boom defenses. Ships required by the army as “covering ships” would be the only ones at sea, they would sail only at night, if possible, and as ships had to anchor for accurate fire, they would be protected by nets, if they had them, during daylight hours. It is not surprising that de Robeck wrote on 16 May: “Now my most important requirement are nets & lighters on which to hang the nets and place them round these ships.”
Hersing and U.21 demonstrated that the antitorpedo nets, which had been such a prominent feature of the prewar battleships, were unable to stop a U-boat’s torpedo. On 25 May he sank the battleship Triumph, and on the 27th the battleship Majestic. The smaller UB boats were less successful; they made Smyrna safely, but only UB.8 sank anything before they reached Constantinople, and that turned out to be a dummy ship, the former transport Merion disguised to resemble the battle cruiser Tiger. Hersing also had less luck when he passed through the Dardanelles on his second mission early in July. He sank the French steamer Carthage (5,601) on 4 July, but the ship had been risked unnecessarily, and U.21 was hindered by the strong Allied countermeasures from achieving further success. The cruise came to a premature end when U.21’s hull was damaged by an underwater explosion, probably a mine. The submarine limped back to Constantinople and was out of action for at least six weeks.
German submarine successes against the Dardanelles expedition in the summer of 1915 did not live up to their promising beginning. UB.14 after completion at Pola was towed by the Austrians through the Strait of Otranto, called at the island of Orak off Bodrum on the Turkish coast, and then operated against the transport route between Alexandria and the Dardanelles, where on 13 August her commander, Oberleutnant zur See von Heimburg, sank the transport Royal Edward (11,117 tons), with a loss of more than nine hundred lives, and damaged another transport before reaching Constantinople. But von Heimburg also found his work hampered by the large number of small craft in the vicinity of the Dardanelles and the weak battery capacity of the UB boats. The UB boats could only carry a very limited number of torpedoes and could only spend a few days on station. The serious submarine campaign against Allied shipping in the Mediterranean did not begin until September and October when the new large boats arrived. It caused great damage, but most of the German successes took place far from the Dardanelles and on the lines of communication.
The arrival of German submarines consequently did not and could not end the Dardanelles expedition. Except for ships foolishly risked, such as the Carthage, the British measures at the Strait were reasonably effective. German submarines found operations off the Strait unprofitable because of wiser British tactics, the hoard of small craft, extensive and heavy net and boom defenses, and eventually shallow-draft monitors for artillery support.
The British and French conducted their own submarine offensive against the Turks. This began even before the commencement of the Dardanelles expedition, when on 13 December 1914 Lieutenant Norman Holbrook in the old B.11 sank the ancient Turkish battleship Messudiyeh near the entrance to the Dardanelles and received the Victoria Cross. The passage through the Dardanelles and the Narrows was extremely difficult, and also tricky because of the current and differences in density between layers of the water that made the craft difficult to control. The British boats were more successful than the less-handy French craft, none of which returned. There is no space in a general history of this sort to tell the story in any detail, but British submarines operated in the Sea of Marmara from April to the end of the campaign. Two of the commanders, Lieutenant-Commander Edward C. Boyle (E.14) and Lieutenant-Commander Martin Nasmith (E.11), won Victoria Crosses. Nasmith sank a steamer anchored alongside the arsenal in the Golden Horn at Constantinople in May, and on another cruise on 8 August sank the Turkish battleship Barbarossa, which had steamed down to support the Turkish defenses at the Strait. E.11 and E.14 made a deliberate attempt to cut the road to Gallipoli where it ran near the water, shelling troops attempting to pass. The Germans and Turks constantly worked at improving their defenses, particularly the Nagara net, and the game grew more and more difficult. The submarines by themselves, however, no matter how spectacular their exploits, could not alter the outcome of the campaign. The British and French each lost four submarines either trying to pass the Dardanelles or in the Marmara. The British claimed 1 battleship, 1 old coast-defense ship, 1 destroyer, 5 gunboats, 11 transports, 44 steamers, and 148 other vessels. There are discrepancies with German figures, possibly because some of the Turkish craft were beached and later salved. The German official history credits British submarines with twenty-five steamers (about 26,000 tons) totally destroyed and ten steamers (about 27,000 tons) badly damaged and out of action for the Dardanelles campaign, as well as the destruction of about 3,000 tons of small craft, for a total of 56,000 tons. The exploits of their submarines were for the British the proudest and most successful aspect of the Dardanelles campaign.