When the American Civil War began in 1861, Brisbin enlisted in the Pennsylvania volunteer services that April as a
private. On April 26, he was appointed a
second lieutenant in the mounted
2nd U.S. Dragoons. He fought in the
First Battle of Bull Run near
Manassas, Virginia, on July 21. In this battle, Brisbin received two wounds, one in his side and the other in an arm, and was praised by his superiors for his performance during the fight. and was wounded in a leg during combat near
Greenbrier, Virginia, on July 26. Brisbin was promoted to
colonel on March 1, 1864, and organized the
5th United States Colored Cavalry. He served as the acting head of cavalry on the staff of Brig. Gen.
Albert L. Lee during the
Red River Campaign, and was again wounded during the
Battle of Mansfield in
Louisiana on April 8, this time in the right foot. On December 12, 1864, Brisbin was
brevetted to
brigadier general in the Union Army, and seven days later was appointed a brevet
lieutenant colonel in the
regular army for his performance at
Battle of Marion in
Tennessee. In 1865, he was on recruiting duty in
Kentucky, serving on the staff of Maj. Gen.
Stephen G. Burbridge. On March 13, Brisbin was brevetted to colonel in the regular army as well as brevetted
major general in the Union Army, and on May 1 he was promoted to brigadier general. Brisbin was mustered out of the Union Army as a volunteer on January 15, 1866. ==Postbellum==