GUIDE TO WWII ALLIED SUBMARINES: HMS UPHOLDER/ TIRPITZ ATTACK/ WAR MACHINE #102
Germany used submarines to devastating effect in the Battle of the Atlantic, where it attempted to cut Britain's supply routes by sinking more merchant ships than Britain could replace. While U-boats destroyed a significant number of ships, the strategy ultimately failed. Although U-boats had been updated in the interwar years, the major innovation was improved communications and encryption; allowing for mass-attack naval tactics. By the end of the war, almost 3,000 Allied ships (175 warships, 2,825 merchantmen) had been sunk by U-boats. The Imperial Japanese Navy operated the most varied fleet of submarines of any navy, including Kaiten crewed torpedoes, midget submarines (Type A Ko-hyoteki and Kairyu classes), medium-range submarines, purpose-built supply submarines and long-range fleet submarines. They also had submarines with the highest submerged speeds (I-201-class submarines) and submarines that could carry multiple aircraft (I-400-class submarines). They were also equipped with one of the most advanced torpedoes of the conflict, the oxygen-propelled Type 95.