sentences:  Her first patrol with this group, from 24 March 1944 to 11 May, found her helping in the search for "U-856", sunk on 7 April by other escorts of the group, and joining in sinking "U-488" on 26 April, when she and three other escorts attacked after the submarine had been spotted by an aircraft from Croatan.Again patrolling across the Atlantic to guard the movement of convoys to Casablanca between 3 June 1944 and 22 July, "Frost" made the initial contact with "U-490" on 11 June.A lengthy attack followed, at the close of which the escorts drew the oxygen-exhausted submarine to the surface by feigning their departure from the area.