 Johnson's Republic P-47D Thunderbolt had been badly shot-up by some Focke-Wulf Fw 190s during a routine mission.As Johnson limped home, with a canopy that would not open and hydraulic fluid and oil covering his windscreen, Mayer pulled alongside him in his Fw 190.Mayer looked the wounded P-47 over, and then circled to come in from Johnson's six-o'clock to give it the "coup de grâce".