No.1-class auxiliary minesweeper

The No.1 class auxiliary minesweeper (第一号型掃海特務艇,) was a class of minesweepers of the Imperial Japanese Navy (IJN), serving during World War II. 22 vessels were planned and built in 1941–43 under the Maru Rin Programme (Ship # 251–256) and the Maru Kyū Programme (Ship # 480–495).

Background

 * In 1938, the IJN was troubled by drifting contact mines from the National Revolutionary Army at Yangtze River. The IJN dispatched a lot of minesweepers and paravane equipment vessels (minelayers, torpedo boats and more) to Yangtze River, but they were damaged by a drifting contact mines too.
 * The IJN wanted a small and light-footed minesweepers. The IJN already commandeered a lot of fishing boats and gave minesweeping operations to them. The Kampon designed minesweeper similar to the trawlers. It is No.1-class auxiliary minesweeper (Project Number I5).
 * They have begun to be commissioned from 1942. However, all of them was dispatched to Pacific front, and they were no match for the magnetic mine because their hull was made by steel.