UNITED STATES OF AMERICA

Project history: By the end of 1930th Bird class minesweepers, making a basis of USN minesweeping forces, have ultimately become outdated. For their replacement in 1938 designing of new ships have begun, which according to sights of Naval staff, besides the main destination, solve still variety of tasks: from ASW service to minelaying.

Similar universality has been bought by displacement growth. Besides the minesweeping equipment new minesweeper could carry 80 mines, sonar and two stern DC racks. The artillery consisted of two 76/50mm DP guns and four 12.7mm MGs.

Experience of an initial stage of war in Europe has unexpectedly revealed serious project lack: new minesweepers were not capable to struggle against magnetic mines. Dense arrangement did not allow to install a diesel-generator necessary for magnetic sweeping gear. The problem was decided by replacing of diesel machinery by diesel-electrical. Despite various machineries, outwardly diesel and diesel-electrical ships practically did not differ from each other.

Only two ships (Raven class) were built under original design, an all the subsequent concerned already to an improved version (Auk class).

During  building of first minesweepers armament structure has undergone some changes: 12.7mm MGs were replaced by 20mm/70 Oerlikons and ASW armament was strengthened by installation of Hedgehog and 4 DCTs. Many ships in 1944-45 had 2 single 40/56 Boforses instead of aft 76/50mm guns and up to 8 Oerlikons.

In total the order on 101 Ravens and Auks has been placed, but in 1943 six of them have refused. 22 ships were transferred to RN by lend-lease.

Modernizations: 1942 - 1943, AM55 - 57: - 4 x 1 - 12.7/90; + 4 x 1 - 20/70 Mk 4

1944 - 45, most of survived early (AM55 - 65, 100 - 131, 314 - 324, 340, 341) ships: - 1 x 1 - 76/50; + 2 x 1 - 40/56 Mk 1.2

1945, most of survived early (AM55 - 65, 100 - 131, 314 - 324, 340, 341) ships: + 4 x 1 - 20/70 Mk 4

early 1960s, most survived: - sweeps

1/1946: 2 x 1 - 76/50 Mk 21/22 or (1 x 1 - 76/50 Mk 21/22, 2 x 1 - 40/60 Mk 3), 8 x 1 - 20/70 Mk 10, 1 x 24 - 178 Hedgehog Mk 10 ASWRL, 4 DCT, 2 DCR, 80 mines (overloaded), sweeps (inc. acoustic and magnetic)

Naval service: Sentinel 10.7.1943 was sunk at coast of Sicily by German aircraft. Skill 25.9.1943 was sunk at Salerno by German submarine U593. Portent was lost 22.1.1944 on a mine at Anzio. Osprey and Tide were lost at coast of Normandy on mines 5.6.1944 and 7.6.1944 respectively. Swerve was lost 9.7.1944 on a mine at Anzio. Skylark 28.3.1945 was lost at Okinawa on a mine. Swallow was sunk 22.4.1945 at Okinawa by kamikaze.

Following ships were damaged by kamikaze at Okinawa: Champion (17.2.1945 and 16.4.1945), Defense (6.4.1945), Devastator (6.4.1945), Gladiator (12.4.1945 and 22.4.1945).