[2] As the United States entered World War II in December 1941, Palmer, then a major, was in the British West Indies working to establish military bases and on anti-submarine warfare projects.

Palmer went to Europe in 1944 as chief of staff of the 2nd Armored Division, then commanded by Major General Edward H. Brooks, and continued in that role during the Normandy invasion, the breakout from Saint-Lô, and crossing the Siegfried Line.

During Operation Dragoon, the Allied invasion of southern France in August 1944, he was chief of staff of the VI Corps, and during this time he received a battlefield promotion to brigadier general.

After retiring from the army, Palmer settled in Washington and worked as a military consultant with the Research Analysis Corporation.

Palmer died in Washington, D.C., on 7 June 1999, at the age of 97 of cardiac arrest in his home in Knollwood, a military retirement community.