Complex sentence: Mayer was killed in action on 2 March 1944 while leading an attack on a USAAF bomber formation; he was shot down by P-47 Thunderbolt escort fighters near Montmédy, France.
Split into simpler sentences: Mayer was killed in action on 2 March 1944 leading an attack on a USAAF bomber formation. He was shot down by P-47 Thunderbolt escort fighters near Montmédy, France.