The 100th Regiment, Indiana Volunteer Infantry, was an infantry regiment that served in the Union Army during the American Civil War. It was one of three Union regiments referred to as the Persimmon regiment. Organized at Fort Wayne, Indiana, and mustered in September 10, 1862, the 100th participated in major campaigns and in 25 battles. The regiment was in the Grand Review of the Armies in Washington, D.C., on May 23–24, 1865, and mustered out on June 8, 1865. It lost during its service 58 officers and enlisted men killed in action or mortally wounded, and 176 by disease for a total of 234 fatalities.