afterwards, as Allied fleets were reinforced and started using better anti-submarine tactics including those learned from the Battle of the Atlantic. By the end of the war, submarines were instead often used to transport supplies to island garrisons. During the war, Japan managed to sink about 1 million tons of merchant shipping (170 ships) with her 184 submarines, compared to 1.5 million tons for Britain (493 ships), 4.65 million tons for the US (1079 ships) and 14.5 million tons for Germany (2,000 ships) with 1,000 U-boats. Early models were not very maneuverable under water, could not dive very deep, and lacked radar. Later in the war, units fitted with radar were in some instances sunk due to the ability of US radar sets to detect their emissions. For example, sank three such in the span of four days. After the end of the conflict, several of Japan's most innovative and advanced submarines were sent to Hawaii for inspection in "Operation Road's End" (I-400, I-401, I-201 and I-203) before being scuttled by the U.S. Navy in 1946 when the Soviets demanded access to the submarines as well. Special Attack Units At the end of World War II, numerous Special Attack Units (Japanese: 特別攻撃隊, tokubetsu kōgeki tai, also abbreviated to 特攻隊, tokkōtai) were developed for suicide missions, in a desperate move to compensate for the annihilation of the main fleet. These units included Kamikaze ("Divine Wind") bombers, Shinyo ("Sea Quake") suicide boats, Kairyu ("Sea Dragon") suicide midget submarines, Kaiten ("Turn of Heaven") suicide torpedoes, and Fukuryu ("Crouching Dragon") suicide scuba divers who would swim under boats and use explosives mounted on bamboo poles to destroy both the boat and themselves. Kamikaze planes were particularly effective during the defense of Okinawa, in which about 2,000 planes were sent to sink 34 warships and damage around 364. A considerable number of Special Attack Units were built and stored in coastal hideouts for the desperate defense of the Home islands, with the potential to destroy or damage thousands of enemy warships. Navy Land Forces The Imperial Japanese Navy Land Forces of World War II originated with the Special Naval Landing Forces, and eventually consisted of the following: Special Naval Landing Force or Rikusentai or kaigun rikusentai or Tokubetsu Rikusentai: the Japanese Marines The Base Force or Tokubetsu Konkyochitai provided services, primarily security, to naval facilities Defence units or Bobitai or Boei-han: detachments of 200 to