Naval History of Japan - World War II

World War II

In the years before World War II the IJN began to structure itself specifically to fight the United States. A long stretch of militaristic expansion and the start of the Second Sino-Japanese war in 1937 had alienated the United States, and the country was seen as a rival of Japan.

To achieve Japan’s expansionist policies, the Imperial Japanese Navy also had to fight off the largest navies in the world (The 1922 Washington Naval Treaty allotted a 5/5/3 ratio for the navies of Great Britain, the United States and Japan). She was therefore numerically inferior and her industrial base for expansion was limited (in particular compared to the United States). Her battle tactics therefore tended to rely on technical superiority (fewer, but faster, more powerful ships), and aggressive tactics (daring and speedy attacks overwhelming the enemy, a recipe for success in her previous conflicts). The Naval Treaties also provided an unintentional boost to Japan because the numerical restrictions on battleships prompted them to build more aircraft carriers to try to compensate for the United States' larger battleship fleet.

The Imperial Japanese Navy was administered by the Ministry of the Navy of Japan and controlled by the Chief of the Imperial Japanese Navy General Staff at Imperial General Headquarters. In order to combat the numerically superior American navy, the IJN devoted large amounts of resources to creating a force superior in quality to any navy at the time. Consequently, at the beginning of World War II, Japan probably had the most sophisticated Navy in the world. Betting on the speedy success of aggressive tactics, Japan did not invest significantly on defensive organization: she should also have been able to protect her long shipping lines against enemy submarines, which she never managed to do, particularly under-investing in anti-submarine escort ships and escort aircraft carriers.

The Japanese Navy enjoyed spectacular success during the first part of the hostilities, but American forces ultimately managed to gain the upper hand through technological upgrades to its air and naval forces, and a vastly stronger industrial output. Japan's reluctance to use their submarine fleet for commerce raiding and failure to secure their communications also added to their defeat. During the last phase of the war the Imperial Japanese Navy resorted to a series of desperate measures, including Kamikaze (suicide) actions.

See also: Imperial Japanese Navy of World War Two