Stewart served with the 5th Infantry at Plattsburgh Barracks from 1912 to 1913. He organized and conducted the Massachusetts officer training school for volunteer reservists in 1913 and 1914, commanded a special experimental training company 1913 and 1914, and served with the 5th Infantry in the Panama Canal Zone from 1914 to 1916. He returned to Plattsburgh in 1916 to lead reserve officer training schools, and later that year received assignment as inspector general of the District of Columbia National Guard. In 1917, he again commanded officer training schools in Plattsburgh, and received temporary promotions to lieutenant colonel and colonel as the Army expanded for World War I.
In late 1917 and early 1918, he served briefly on the Army's general staff, and then received assignment as chief of staff for the 76th Division. After serving in France with the 76th Division, Stewart received promotion to temporary brigadier general and assignment as commander of 175th Brigade, 88th Division.[3]
After the war, Stewart returned to the permanent rank of major and commanded an Overseas Replacement Depot at Fort Meade, Maryland, served again at Fort Leavenworth and on the Army General Staff, and received promotions to permanent lieutenant colonel and colonel. In 1923 Stewart was assigned as Commandant of Cadets at West Point. He served until retiring in 1927, and received promotion to permanent brigadier general in 1925, and major general at his retirement.
The President of the United States of America, authorized by Act of Congress, July 9, 1918, takes pleasure in presenting the Army Distinguished Service Medal to Brigadier General Merch Bradt Stewart, United States Army, for exceptionally meritorious and distinguished services to the Government of the United States, in a duty of great responsibility during World War I. As Senior Instructor at the Plattsburg Training Camp from May until August 1917, General Stewart displayed organizing and training ability and talents of the highest order, in successfully directing the training and selection of 6,000 officer candidates, thereby rendering services of inestimable value to our newly-formed forces. As Chief of Staff, 76th Division, from August 1917 until June 1918, he again showed tireless energy, practical resourcefulness, and military attainments of the highest order. Later, as Commander of the 175th Infantry Brigade, 88th Division, he performed his duties with marked ability and excellent judgment.[4]
Personal life
Stewart married Nan Wheelihan of Wisconsin on February 16, 1898. They had one son: Peter.[5]
Stewart, M.B.; Moss, Jas. A. (1917). Our flag and its message. Appeal by Woodrow Wilson. Philadelphia and London: J.B. Lippincott Company. pp. 31. Retrieved May 2, 2009.
Stewart, M.B. (October 19, 1919). "DEMOCRATIC MILITARY TRAINING". The New York Times. New York City. Retrieved January 8, 2010.
Stewart, M.B.; Waldron, W.H. (1920). Thirty Minute Talks. Washington D.C.: United States Infantry Association. pp. 379. Retrieved May 2, 2009.