On March 6, 1944, Blakeslee flew in the first Mustang over Berlin while defending Boeing B-17s and Consolidated B-24s. Escorting the massed daylight raids of the 8th Air Force over Occupied Europe while under Blakeslee's command, the 4th FG became one of the highest-scoring groups of VIII Fighter Command. The 4th's aggressive style was very effective, and the 4th Fighter Group passed the 500-kill mark at the end of April 1944. At the end of the war, the group had destroyed 1,020 German planes (550 in flight, and 470 on the ground).