during the course of the interdiction operation , an air battle Hostile_encounter known as the 18 april `` unk unk '' ( `` palm sunday massacre Killing '' ) took place Process_start , in which the german junkers ju 52 transport fleets suffered Bodily_harm heavy losses Earnings_and_losses over cape bon while evacuating Removing `` heer '' ( german army ) forces Military_operation escaping Escaping from the allied ground offensive Hostile_encounter operation `` vulcan '' .