 Garrison recorded his first combat victory returning from a bomber withdrawal support mission to Bremen on December 16, 1943.In exceptionally bad winter weather conditions, he shared credit for shooting down a Junkers Ju 88 fighter over the German-Dutch border with Don Gentile and Louis Norley.A month later, on January 14, 1944, he downed two Focke-Wulf Fw 190s, although his claim report for the second kill credited half to Norley.