Muir received an appointment to the
United States Military Academy (USMA) at
West Point, New York in 1881, graduating eighth in his class in 1885. Among his classmates included several officers who would become future
general officers, such as
Beaumont B. Buck,
Joseph E. Kuhn,
Henry P. McCain,
Robert Michie,
George W. Burr,
John D. Barrette,
John M. Carson Jr.,
Robert A. Brown,
Robert Lee Bullard,
William F. Martin,
Daniel B. Devore and
Willard A. Holbrook. After receiving his commission as a second lieutenant in the United States Army, Muir was sent to
Dakota Territory and later to
Fort D. A. Russell in
Wyoming. He held first place on the Army Rifle Team in 1890. In 1895, Muir graduated at the head of his class from the Infantry and Cavalry School in
Fort Leavenworth in
Kansas. Muir was deployed to
Cuba during the Spanish–American War, where he received the
Distinguished Service Cross for gallantry in action during the
Battle of Santiago de Cuba. On July 2, 1898, he had voluntarily exposed himself to heavy enemy
artillery and
infantry fire in an action which resulted in the silencing of a piece of Spanish artillery. ,
Meuse, France, October 31, 1918. Stood to Muir's left is his
chief of staff, Brigadier General
Briant H. Wells while
Joseph Stilwell, then a major, stands to his right in the rank behind. Muir was promoted to captain on 2 March 1899. Later that year he was promoted to major and sent to the
Philippines. On 19 January 1900, Muir and ten other American soldiers attacked the headquarters of General
Miguel Malvar at
Rosario in
Batangas province, driving Malvar and his men out. Muir's unit took possession of 25,000 Mexican pesos from Malvar's treasury and released 300 Spanish prisoners. From 1903 to 1907, he was a member of the
general staff at
Washington, D.C. Major General Muir succeeded
Charles M. Clement as Commander of the
28th Division from 15 December 1917 until 23 October 1918, when he was succeeded by
William H. Hay. Muir commanded
IV Corps, aided by
Briant H. Wells as his
chief of staff, until April, 1919 when he succeeded Hay as commander of the 28th Division and led it to the United States for its post-war demobilization. He was succeeded by
William G. Price Jr. when the division was reorganized as part of the
Pennsylvania National Guard. From July 1919 to August 1920, MG Muir served as
Commandant of the United States Army Command and General Staff College. His final duty assignment was at the
War Department in Washington, D.C., after which he retired from the army with the permanent rank of major general. ==Awards==