Submarines of the Imperial Japanese Navy
The Imperial Japanese Navy's doctrine of fleet warfare ("guerre d'escadre") resulted in its submarines seldom posing a threat to allied merchant convoys and shipping lanes to the degree that the Kriegsmarine's U-boats did as they pursued commerce raiding against Allied and neutral merchant ships. During the war, IJN submarines did sink about 1 million tons (GRT) of merchant shipping (184 ships) in the Pacific; by contrast U.S. Navy submarines sank 5.2 million tons (1,314 ships) in the same period, while U-boats of Nazi Germany's "Kriegsmarine", the IJN's Axis partner, sank 14.3 million tons (2,840 ships) in the Atlantic and other oceans. During the last two years of the War in the Pacific, many IJN submarines were also occupied serving to transport supplies to isolated island garrisons, ones that had been deliberately bypassed by the Americans and the Australians and which could not be reached by surface transports because of blockade by Allied warplanes and naval vessels.
List of warships sunk during the Russo-Japanese War
Although submarines, torpedoes, torpedo boats, and steel battleships had existed for many years, the Russo-Japanese war was the first conflict to see mature forms of these weapon systems deployed in large numbers. Over a hundred of the newly invented torpedo boats and nearly the same number of torpedo boat destroyers were involved. The Imperial Russian Navy would become the first navy in history to possess an "independent operational submarine fleet" on 1 January 1905. With this submarine fleet making its first combat patrol on 14 February 1905, and its first clash with enemy surface warships on 29 April 1905, all this nearly a decade before World War I even began.