The 1st Regiment Cavalry of Colorado was made up of volunteers from Colorado citizenry. It was organized in Denver in 1861, having been converted to cavalry from an infantry unit. During the Civil War years, this regiment fought mostly with Indians and guerillas.

The collection contains twenty-one items including special orders, reports, monthly returns by the quartermaster, invoices, inventories, muster rolls, and letters. The bulk of the collection comprises operational documents related to equipment and supplies for the regiment. One of the documents regarding receipt of clothing is a roster of Company D, signed by each individual. Special orders concern scouting and establishing camps near Pueblo, and between Huerfano and Purgatoire. Most duty orders came from Fort Lyon. Other items include a bond note for a man released from imprisonment for being a Confederate sympathizer; a list of returned contraband and confiscated property; and a report on a mission accomplished, noting names of those killed or taken prisoner. A muster roll of the Provost Guard of the regiment dates from Dec. 31, 1864 to Feb. 28, 1865. Thirteen of the documents are addressed to, or signed by, Lieutenant and later Captain Silas S. Soule, who was based in Denver.