Their principal components are frigates, corvettes, and minesweepers. Fleet minesweepers such as the were rated as "minesweeping sloops". Operation Overlord saw an enormous minesweeping operation, with hundreds of minesweepers clearing and maintaining channels. Three minesweepers, , and , then entered the bombed channel to resume minesweeping. The four planned destroyers were replaced by four German M-class minesweepers. There are four minesweepers consisting of 2 Sonya class minesweeper and 2 Yevgenya class minesweepers. Polish shipyards produced mostly landing craft, minesweepers and auxiliary vessels. Eight were converted to destroyer minesweepers (DMS). China also had four warships present&colon; the PLA Navy minesweepers "271", "274", "389" and "396". There were, in addition, many corvettes, minesweepers, and other small vessels. Mines and shellfire sank or damaged 11 minesweepers. Two minesweepers were sunk in these operations. MCM vessels have mostly legacy names of previous US Navy ships, especially WWII-era minesweepers. On 12 October 1950, two U.S. minesweepers hit mines and sank. Two other Japanese minesweepers were also damaged by mines.