Dean was born on May 12, 1865, in
Ironton, Ohio. He graduated 52nd in a class of 64 from the
United States Military Academy in 1887. Among his classmates who also became general officers were
Frank Herman Albright,
Marcus Daniel Cronin,
Alexander Lucian Dade,
Charles S. Farnsworth,
George Washington Gatchell,
Charles Gerhardt,
Herman Hall,
Thomas Grafton Hanson,
Mark L. Hersey,
Ernest Hinds,
Michael Joseph Lenihan,
Ulysses G. McAlexander,
Nathaniel Fish McClure,
William C. Rivers,
George Owen Squier,
Charles Brewster Wheeler, and
Edmund Wittenmyer. Commissioned in the
3rd Infantry Division, Dean frequently worked in the area of ordnance. Dean served as an aide to Major General
John R. Brooke between 1893 and 1895 and again from 1899 to 1902. During the
Spanish–American War, he served as the Chief Ordnance Officer in
Cuba and
Puerto Rico. After returning to the U.S., he served in the
District of Alaska from 1906 to 1908. Graduating from the
United States Army War College in 1911, Dean served in the
Philippines from 1912 to 1915. Dean was temporarily promoted to the rank of
brigadier general on August 5, 1917, and assumed command over the 156th Infantry Brigade which he went with on a tour of duty in France. he commanded the
78th Infantry Division between March 16 and April 20, 1918, and he participated in the
Battle of Saint-Mihiel as well as the
Meuse-Argonne Offensive. Reverting to the rank of
colonel after the war, Dean commanded the
20th Infantry Regiment before moving to the Adjutant General's Department. After serving two years as an adjutant of the Philippine Department in Manila, Dean commanded the
11th Infantry Regiment for another two years. On April 23, 1924, he began overseeing military recruitment in the New York area, and after this, he served as the Chief of Staff of the
77th Infantry Division. Dean retired on September 3, 1928, with his retirement rank being reinstated as brigadier general on June 21, 1930. He died on June 15, 1939, at his summer home in
Gracefield, Quebec,
Canada. ==Personal life==