African American soldiers served in the Revolutionary War and fought for the Union in the American Civil War. Six black cavalry-infantry units were officially organized on September 21, 1866 at Fort Leavenworth, Kansas, and served across the West from Kansas and Oklahoma to Texas and Arizona, earning a formidable reputation as first class soldiers. The 9th and 10th Cavalry and the consolidated 24th and 25th Infantry Regiments remained active until 1952, when black troops were integrated into the regular Army. The men of the 9th and 10th were the first Buffalo Soldiers, a name given by Cheyenne and other tribal adversaries and accepted as an honor. In 1892, the black cavalry-infantry units were transferred from Fort Grant, Arizona to Fort Custer in Montana under Colonel J.K. Mizner, with troops stationed at Forts Custer, Keogh and Assiniboine in Montana and Fort Buford in North Dakota. Fort Assiniboine became regimental headquarters in 1896. Among the regiment's white officers was Lieutenant John J. Pershing, later a brigadier general of international renown. In 1898, Pershing left West Point at his own request to rejoin Fort Assinniboine's 10th Cavalry for service in Cuba during the Spanish American War and Philippine Insurrection, where he and his men fought alongside Theodore Roosevelt's Rough Riders at San Juan Hill. One eyewitness said that without the Negro cavalry the Rough Riders would have been exterminated. Horace W. Bivens, one of the 10th Cavalry's non-commissioned black officers at Fort Assinniboine, served more than thirty years and received 32 medals, including the Silver Star for valor at San Juan Hill; his Army marksmanship record remained among the highest on record. An 1897 regimental history of the 10th Cavalry credited its veterans in no small degree with the settlement and civilization of the Great West and honored the devotion, toil, suffering, valor, and sacrifice of regular soldiers, including many who died in unknown graves.