Accounts of the Japanese submarine exercises of 1939-41 clearly show that Japanese navy training attempted to be comprehensive, rigorous, and innovative in the development of the submarine as a weapon to attack regular fleet units. Tactical training was carried out at night as well as during daylight. Long- and short-distance operations were practiced. Coordination was attempted between submarines and aircraft. New weapons, like the type 95 torpedo, were tested, and novel techniques, such as “submerged firing,” were practiced.
Japanese submarine commanders developed zembotsu hassha (submerged firing) because, although their boats had proper range finders and devices for ascertaining exact bearing, they could only be used on the surface. Preferring to stay submerged when attacking fleet units screened by destroyers, submarine commanders would submerge, expose the periscope for a final optical reading of bearing and range, keep the periscope down for the final closure to the firing point, and then fire on sound bearings. This technique was hardly unique to the Japanese navy; American submarine commanders practiced something very much like it (“sound shots”) before the war, but having little luck, dropped them.
It is not surprising that the Japanese also developed the idea of naval air war to make up for numerical inferiority in battleships to the US Navy. It was generally assumed that they were to fight the decisive battleship engagement somewhere in the Western Pacific. With the 10:6 advantage the Americans enjoyed, even after the US Navy suffered from wear and tear during the long voyage from the American West Coast to the Western Pacific, they’d still enjoy their superiority. The Japanese naval men therefore sought to reduce American battleship strength by naval guerrilla war at sea. Using aircraft and submarines, the Japanese would set up a series of ambush points along the most likely lines of American advance. By hit and run tactics, they would try to damage or sink American battleships before they could reach anywhere near Japan. By the time they had their naval showdown, hopefully, the opposing battle fleets would have a rough parity in the number of battleships they could deploy. Then, the Japanese believed, they would enjoy advantage over the Americans as they were fighting closer to home. They were more highly motivated as they were defending their own home country; their sailors were in a fresher state, in contrast to the tired Americans; and their battleships would be better serviced and in an optimal condition to fight a fleet battle.
During the 1930s, Japanese thinking drifted towards more offensive-defensive ideas. At first, many naval thinkers, both Japanese and Western, believed in the idea of a naval showdown in or near Japanese waters or the Philippines. Towards the eve of the actual war in the Pacific, however, the Japanese were getting increasingly reluctant to wait until the American navy came to them. Surely, Americans would not repeat the mistake of the Russians? They’d rather fight the decisive battle on the ground of their own choosing. And so would the Japanese. Moreover, the Japanese valued offensive spirit. The idea of fighting a defensive naval war simply because they had fewer ships than their opponent just didn’t sit well with their mentality. Admiral IsorokuYamamoto, who was the overall commander of the Japanese naval forces since the summer of 1939, thus sought to deliver a massive blow to the US fleet at the very opening of hostility in a surprise attack, aiming at destruction of not just the US fleet but also that of morale of the US public. In order to do so, Yamamoto could not risk losing any of his battleships as they had to be preserved for the coming showdown, so he preferred using naval air forces to achieve this.
Therefore, the ‘naval revolution’ which the supposed genius of Yamamoto initiated was to a large extent just a logical extension of the battleship era thinking. In fact, most Japanese naval leaders continued to think in terms of fighting a decisive fleet action by big gun battleships. Yamamoto certainly believed in the power of naval air arm, more so than most of his colleagues, yet it is doubtful he thought that airpower could completely replace the battle fleet. Airpower was only useful to keep American battleships at bay while Japan could achieve its strategic aim of destroying US morale, which was the most vital war aim for him. Yamamoto, who had lived in America for a few years, was too aware of massive economic and industrial potential of the US. He felt that unless American will to fight could be destroyed, the US would simply outbuild Japan. How does he achieve this? The Japanese navy had to win and win big so much so that Americans would get so discouraged to fight war thousands of miles from their own home. Waiting for the US to mount its offensive, even a Japanese win in a defensive sea battle would not affect American morale that much. To reduce American battleship strength, his naval air forces would strike en masse, delivering a crippling blow to the US battle fleet to such an extent the final battleship duel would even be unnecessary. His aim was, ideally, a total sea denial to the US naval forces in the western Pacific.
Thus, another point that is not widely recognised is that Japanese strategic thinking was defensive in orientation. As Japan was waging a very aggressive war of conquest, there is a general sense that Japan’s war with China and the Western allies were an offensive war aimed at imperial expansion. However, Japanese thinking was dominated by concerns for defence of what they considered as their sphere of influence. On a map, Japanese gains from the end of 1941 up to the summer of 1942 look impressive. What they achieved was large territorial expanses to ensure that Japan would keep a self-sufficient, autarkic empire. Only by achieving such goals, their country’s social stability, economic welfare of its people and respectability in the new international community would be ensured, or so did they believe.
Therefore, both their strategic and political goals was to acquire colonies to build and defend an empire and force the Western Allies to accept the fait accompli. Given the level of threat the US and the Allies posed, the Japanese thought, Japan needed to acquire and control as much territory as possible, in order to absorb the shock of American counter-attack. In May 1942, Japan was embarking on what appeared to be the conquest of Australia, landing troops in New Guinea. This operation was in fact designed to cut off communication between Australia and the US mainland, and so to deny the Americans the use of Australia as the base for the anticipated counter offensive. They wanted to keep the Americans in check just long enough. They knew they could not fight a long war, even though they did not know how to ensure the war would be short. They just hoped that the US would be too busy with war with Germany and the US public was not very keen on war for Asia. By the time the war weary US public forced their government to sue for peace, Japan’s empire should still be large enough to maintain its territorial and economic integrity. In hindsight, they utterly underestimated the US public’s ability to endure a long, bloody war. Some Japanese naval men suspected that their plans were based on unrealistic assumptions, but political atmosphere of the day made them hesitate to admit the doubt, let alone to speak out.
A few did. In the early 1941, Rear Admiral Shigeyoshi Inoūe was one of the least popular figures in the Imperial Japanese Navy because he often called his fellow admirals stupid. When the navy put forward a plan for a massive naval expansion to keep pace with the latest American naval programme in anticipation of war, he shocked his colleagues by allegedly blasting, ‘Who came up with this? Are you retards or something?’ This caused consternation among other admirals. Japan was about to launch her war against America within several months. Strategy had been agreed upon and a new naval building programme had been approved. Now he’s saying what they are doing is nonsense! The insulting way he put it made them even more angry. They demanded that Inoūe articulate what he would do then. In response, he produced a short paper presenting his views. While, in hindsight, his proposals do not show great spark of genius, when it comes to what the US would do, he was so dead-on, if anyone should be called a prophet of war, Inoūe is the one who fits the bill.
His thinking shows strong British influence. But he did not just copy British ideas. Like his British counterparts at Greenwich, he worked the problem from the very basics: geography and technology.
Geographically, he pointed out, a big, continental country like the United States had an advantage of strategic depth. It was simply impossible for Japan to invade the continental America and to reach its capital. Japan could not hope to wipe out American military forces. On the other hand, the US was capable of doing this to Japan and taking even the capital Tokyo.
He also pointed out that the sheer vastness of the Pacific Ocean meant that the likelihood of the decisive battleship action happening was practically nil. Finding an enemy battle fleet alone would be next to impossible. He also asked, surely you don’t expect Americans to be stupid enough to rush to fight our fleet prematurely only so that we could annihilate their battleships? Indeed, the Japanese were to be frustrated by lack of opportunities to use their super battleships for a showdown. The biggest battleship ever built, the Yamato, failed to sink anything of value throughout the war.
As Inoūe repeatedly insisted that aircraft and submarines changed naval warfare so fundamentally, his enemies attacked him as self-interested, for he was the head of naval aviation of the Japanese Navy at the time. Nevertheless he was certainly correct that the US would employ submarines in the western Pacific to disrupt Japanese sea communication. Hence, he preached that Japan needed to devise anti-submarine strategy and tactics, though he could not offer anything in detail, as Japan had little experience in this area of naval warfare. The British experience during WW1 was the only guide: all he could do was to recommend that more escort ships should be built for convoy duties.
Remarkably, Inoūe predicted the island hopping campaign employed by the Americans. To him, this was only logical. While the British emphasised that sea control must be established by winning major fleet actions, he understood that without winning bases and facilities, sea control could not be won. For warships without fuel were useless. Therefore, what was to come was a series of deadly struggles for bases, which were mostly on tiny islands in the Pacific. Only by winning this contest, Japan had any realistic chance of winning war.
He even went on to say that the navy could afford to sacrifice battleships and heavy cruisers as they would be of little practical value. This naturally did not go down well with his peers (and on this he was perhaps wrong, as the US Navy actively used these types of ships for escort and anti-air duties and shore bombardment), as the belief in decisive battleship action was too strong.
Most Japanese officers spurned Inoūe’s views. Unfortunately his battlefield performance did not help either. He was the overall commander of the task force to attack Australia in the spring of 1942. In the ensuing battle, known as the Battle of Coral Sea, he managed to sink the US carrier Lexington, while losing one light carrier of his own (the Shoho) and getting a fleet carrier (the Shokaku) damaged. Thus he called off the operation, for he feared that aircraft carriers were too vulnerable to enemy attack and did not want to take unnecessary risks. For this he was considered as lacking offensive spirit and was removed from command. He was unpopular as a mouthy and brainy aristocrat (he was of old Samurai stock) without charisma or killer instinct, unlike the popular Yamamoto. He was to be made full Admiral only towards the end of the war when some Japanese leaders began to realise that Japan was losing and that someone had to represent Japan in search of peace with the Allies. For this, he was derided as an admiral who was only good at losing.
Most regrettably, his political views were totally ignored and overruled before the war. He was against war with the US and thought it unwise to jump on the ‘German bandwagon.’ After Japan’s defeat, Admiral Inoūe retired unceremoniously and lived quietly and in poverty, earning meagre living by teaching children English and music. It was long after the war his predictions of US strategy were belatedly recognised by the astonished Americans. It was only after his death that some of his pupils and friends began to see his talent and insight. In 1941, however, no one would listen to him. The war was on.