January - December 1944, Moving in on Japan
Overview:
Throughout 1944 the Allies stepped up their efforts to interdict Japanese shipping in the waters bordering the Home Islands. American submarines sank 52 vessels within Japan’s littoral waters, 12 nautical miles from shore. This represented a 51% increase from 1943. Additionally, U.S. subs dramatically increased their attacks on Japanese merchant vessels along shipping lanes which connected the Home Islands to Okinawa and Iwo Jima. Lastly, 1944 saw a marked increase of sinkings between the Japan and an its territorial holdings in Korea and China.
By 1944 the Allied navies, particularly the United States submarine fleet corrected the systemic issues which plagued the force during the early stages of the war. Combat experience led to better tactics and training. As the quality of the submarine force improved, so did its quantity. By January 1944 the U.S. Navy had at its disposal 75 submarines as compared to only 53 the year before. These new Gato, Balao, and Tench class vessels were more advanced, better armed and more capable submarines. Their availability relegated obsolete, pre-war S class subs to training and noncombat duty thereby improving the capability of the fleet as a whole.
As the Japanese empire collapsed, Japan began moving its prisoners of war (POWs) and slave laborers toward destinations nearer to mainland Japan. Crammed aboard merchant ships, Allied POWs and slave laborers fell victim to submarines unaware of their targets' status as prisoner transports. On 12 September 1944, the Rakuyo Maru was sunk by the USS Sealion (SS-315). Of the over 1,300 Australian, and British POWs aboard the ship, 1,159 died. The same day, the USS Pampanito (SS-383) torpedoed the Kachidoki Maru, a transport carrying over 950 Allied POWs. Sinking in only three minutes, 431 POWs died in the attack. Several days later, on 18 September, the Junyo Maru was sunk by the HMSM Tradewind, a British submarine operating off Sumatra. Its hold filled with thousands of Allied POWs and Javanese slave laborers known as romushas, the Junyo Maru went down taking over 5,500 lives in one of the worst maritime disasters of World War II.
Expanded Legend
- U.S. subs and naval aircraft sunk 94 merchant vessels between the Japanese Home Islands and Iwo Jima and the Bonin Islands throughout 1944. These raids resulted in the elmination of this shipping route by the end of the year and the isolation of Mariana Islands from Japan. Only four vessels were sunk in these waters through all of 1945.
- Swinging in southernly arc, the shipping lane between Formosa and the Japanese southern island of Honshu extended through the Ryukyu Islands. Within this route Allied forces sunk 52 Japanese merchant vessels. US submarines attacks accounted for 42 vessels. Navy carrier-based aircraft launched a major air raid in preperation for the U.S. invasion of Okinawa, sunk eight ships on 10 October alone.
- Allied submarine activity increased markedly in the Yellow and East China Sea in 1944. U.S. subs sank 118 vessels, 45% more than 1943.
The rescue of weakened and oil-soaked Australian and British survivors of the Rakuyo Maru was captured in color footage on 15 September 1944.