In 1922, he received his commission as a second lieutenant in the 56th Cavalry Brigade, and he advanced through the ranks in command and staff positions, primarily as a member of the Texas National Guard's 36th Infantry Division.

During World War II, Kerr served in Europe as the 36th Division's inspector general and chief of staff, and later as U.S. Representative to and Deputy Commander of the Allied Military Mission to the Italian Army.

In 1964, received a state promotion to lieutenant general as recognition of his accomplishments and years of service.

[2] In September 1918, he joined the National Guard as a member of Headquarters Troop, 6th Texas Cavalry, and he took part in patrols of the Texas-Mexico border during the closing months of World War I.

[3] In March 1919, he was scheduled to take the entrance examination for the United States Military Academy, but opted instead to continue his National Guard career.

[14] Kerr was a frequent contributor of articles to professional journals and other publications, including 1944's "Joint Maintenance in Theater Operations".

[16] Kerr was one of the original officers who formed the Texas Army National Guard’s 49th Armored Division.

[22] Kerr continued to author articles on military topics, including 1959's "Training an Army National Guard Armored Division".

[30] In 1964 Governor John Connally recognized Kerr's accomplishments and long years of dedicated service with a state promotion to lieutenant general.