Complex sentence: Colonel Donald Blakeslee was a pilot in 121 and 133 Squadrons during 1942, making 120 sorties and claiming 3 air kills, became deputy commander of the 4th Fighter Group under Chesley Peterson, then commanded the group from January to October 1944.
Split into simpler sentences: Colonel Donald Blakeslee was a pilot in 121 and 133 Squadrons during 1942, making 120 sorties and claiming 3 air kills. He became deputy commander of the 4th Fighter Group under Chesley Peterson, then commanded the group from January to October 1944.