In 1855, the United States Congress recognized the need for mounted regiments in the U.S. Army in addition to the First and Second Regiments of Dragoons and the Regiment of Mounted Riflemen. The 1st Cavalry Regiment—later re-designated as the 4th Cavalry Regiment—was organized under the act of 3 March 1855. On 26 March 1855, the regiment was organized at Jefferson Barracks, Missouri. The regiment's first commander was Colonel Edwin V. Sumner, who served from 3 March 1855 to 16 March 1861. In August 1855, the regiment was transferred to Fort Leavenworth, Kansas. Colonel Sumner had two missions. The first was to keep the peace between the pro-slavery and free state factions in Kansas; the second was to protect settlers from attacks by Cheyenne warriors.