3rd Regiment Indiana Cavalry

The 3rd Regiment Indiana Cavalry, also designated the 45th Regiment Indiana Infantry or the 45th Regiment Indiana Volunteers was a military unit from the U.S. state of Indiana that participated in the American Civil War. It consisted of two separate "wings" that never operated together:

• The 3rd Regiment Indiana Cavalry (East Wing) (or Right Wing), consisting of Companies A, B, C, D, E and F, organized at Madison, Indiana, August 22, 1861, that were intended for service with the 1st Regiment Indiana Cavalry. On October 22, the six companies were designated the 3rd Cavalry and assigned to the Army of the Potomac in the Eastern Theater of the war. The East Wing saw action at the Battle of Antietam.

• The 3rd Regiment Indiana Cavalry (West Wing) (or Left Wing), consisting of Companies G, H, I, K, L and M. The first four companies were organized at Madison on October 1, 1861. In December, they were assigned to the Army of the Ohio. Company L, organized in October 1862, and Company M, organized in December 1862, later joined the unit in Eastern Tennessee. The West Wing saw action at the Battle of Chickamauga. In December 1864, the West Wing companies were transferred to the 8th Regiment Indiana Cavalry.