The 1st DC Cavalry was mustered in for 10 months' service on October 23, 1863 and were mustered out on August 27, 1864 and the remainder of the regiment was transferred to the 1st Maine Cavalry. Of the 1,017 men enrolled in the regiment, 27 were killed or died of wounds, 27 died of disease, and 1 died in prison.

This Regiment was an independent organization designed for special services in Washington, D.C. The first officers were commissioned by the President of the United States. The later companies had their officers commissioned by Maine's Governor. The regiment did not arrive in Washington at the same time, but over a period of time covering the end of October to the end of February 1864. Part of this regiment went to Portsmouth, Virginia for guard duty and the remainder joined General Butler's Army. That part that joined General Butler saw action around Petersburg. After a heavy engagement at Sycamore's Church and Cox's Church, the remainder of the regiment went to the First Maine Cavalry.

They served in the following engagements:

• Kautz's Raid - May 5 - 20, 1864
• Weldon and Petersburg Railroad - May - June, 1864
• Malvern Hill - July 26, 1864
• Picket duty on railroad - August 21-24, 1864
• Ream's Station - August 24, 1864
• Transfer to 1st Maine Cavalry - August 27, 1864
• Sycamore's Church (still as D.C. Cavalry) - September 15, 1864
• Cox's Church - September 15, 1864