Kammala jumla mai zuwa: M21 ya yi aiki a Yammacin Yamma, yana ganin aikin a Normandy da kuma a
Kudancin Faransa, kafin daga baya a yi amfani da shi a lokacin Yaƙin Bulge, Yaƙin Belgium, Operation Market Garden, da mamayewar Jamus daga yamma. M21 ya yi aiki tare da sojojin Amurka na 3, 1st, da 7th a lokacin yakin a Faransa, da kuma 2nd Armored Division, wanda ya ci gaba da shi. Bugu da ƙari, an ba da misalai 57 ga sojojin Faransawa 'yanci. A shekara ta 1945, an ayyana shi a matsayin wanda ba shi da amfani, saboda rashin isasshen wutar lantarki na 81 mm a matsayin bindigar bindiga.