On February 24, 1894, Palmer was awarded the Medal of Honor for his actions as colonel leading the 15th Pennsylvania Cavalry at Red Hill, Alabama, January 14, 1865 where "with less than 200 men, attacked and defeated a superior force of the enemy, captured their fieldpiece and about 100 prisoners without losing a man." Six former officers of the 15th Pennsylvania Cavalry had nominated him the previous October to receive the honor, but for the scouting efforts in mufti during the Antietam Campaign that resulted in his capture. The War Department rejected that nomination on the basis that the acts, while valorous, had not been performed of a field of battle. They then submitted a new nomination for the action at Red Hill, which was approved.