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.
Imperial Russian Navy
Due to the ongoing blockade of Port Arthur in 1904, the Imperial Russian Navy dispatched their remaining submarines to Vladivostok, and by the end of 1904 the last of seven subs had reached their new base there. Using the seven boats as a foundation, the Imperial Russian Navy created the world's first operational submarine fleet at Vladivostok on 1 January 1905. On 14 February 1905 the new "submarine fleet" sent out its first combat patrol consisting of the vessels "Som" and "Delfin". With patrols varying from 24 hours to a few days, the sub fleets first enemy contact occurred on 29 April 1905 when Imperial Japanese Navy torpedo boats fired upon "Som", withdrawing after failing to score a hit. On 1 July the Russian submarine "Keta" made contact with two Japanese torpedo boats in the Tartar Strait. "Keta" could not submerge quick enough to obtain a firing position and both adversaries broke contact.