Type D submarine

After the Battle of Midway the IJN immediately planned a transport submarine. The type was based on the U 155 Deutschland. Her duties were transportation of troops (110 men, 10 tons freight and two landing craft) in the areas where the enemy had air superiority. Later the demands for her were changed in sequence. The final demands were 65 tons in the hull and 25 tons on the upper deck (freight only). In the beginning the IJN did not intend to arm these boats with torpedoes. Later, after strong demands from the front commanders, it was decided to arm them with torpedoes for self-defense. The I-372 class was designed as a tanker submarine based on the I-361 class. They were not allowed to be loaded with torpedoes. ==Service==

In 1944, the submarines were tasked with transport missions between from mainland Japan to remote islands. They had little success and suffered great losses. Of the 13 submarines, only four survived the war. ==Kaiten missions==

In 1945, several submarines were converted to be Kaiten mother ships and assigned to the suicide attack operations for the . Their deck guns were removed and fittings for five Kaitens were installed on their decks. • • Assigned to the on 24 May 1945, no success. • • Assigned to the Todoroki group on 28 May 1945, sank (or damaged) one motor ship on 15 June 1945. • Assigned to the on 8 August 1945, no success. • • Assigned to the Tamon group on 1 August 1945, no success. • • Assigned to the on 5 May 1945, damaged USS Gilligan on 27 May 1945. • Assigned to the Tamon group on 19 July 1945, no success. • • Assigned to the on 20 February 1945, no success. • • Assigned to the Chihaya group on 20 February 1945, no success. Image:Japanese submarine I-363.jpg|I-363 in May or August 1945 Image:Japanese submarine I-367.jpg|I-367 on 19 July 1945 Image:Japanese submarine I-370.jpg|I-370 on 21 February 1945 ==Class variants==

The Type-D submarines were divided into four classes: • • • • . The 2968th vessel class boats were not built and remained only a design. I-361 class I-372 class Project number S51B. She was going to become a lead ship of the Modified Type D submarines (I-373 class), at first. However, the IJN wanted a submarine as soon as possible. She was built as a tanker submarine according to revised I-361 drawings. I-373 class Project number S51C. Improved model of the I-361 class. Furthermore, the IJN was planned reinforced model of the I-373 class, also. However all of them were cancelled. ==Footnotes==