The 1st Naval Armaments Supplement Programme, otherwise known as the "Circle One Plan" was the first of four expansion plans of the Imperial Japanese Navy between 1930 and the start of World War II.
IJN cruisers Mogami, Mikuma, Kumano all constructed under the "Circle One" plan
Ryūhō was a light aircraft carrier of the Imperial Japanese Navy. She was converted from the submarine tender Taigei, which had been used in the Second Sino-Japanese War. One of the least successful o
1st Naval Armaments Supplement Programme
…tactics. In a 1932 supplement to the Circle One plan, additional funding was added for the construction of three more vessels: the submarine tender Taigei, and two submarine chasers. 2nd Naval Armaments Supplement Programme (Maru 2 Keikaku, 1934…
Ryūhō in 1942
Japanese submarine depot ship Taigei off Kure in 1935
Hangar deck of Ryūhō, 9 October 1945