Born March 15, 1811 West Point, Morrow County OH
USMA bottom third in 1836
Died August 5, 1886 Geneva, Switzerland while traveling
Buried Chène-Bougeries Cemetery

Allen was born in tiny West Point in Columbiana County, Ohio, and was educated in the public schools. He received an appointment to the United States Military Academy and graduated in 1836, ranking 33rd out of 49 cadets. He was assigned as a second lieutenant in the 2nd U.S. Artillery and assigned to garrison duty in various outposts.

He saw his first combat during the Mexican-American War, where he received a brevet promotion to major for his actions at the Battle of Cerro Gordo. Allen was transferred to the Quartermaster's Department, and was eventually promoted to the chief quartermaster for the Department of the Pacific with the permanent rank of major.

At the outbreak of the Civil War, Allen was reassigned to the Department of the Missouri, where he was again chief quartermaster, as well as a colonel. Becoming recognized for his efficiency, he was soon promoted to command the supplies for the entire Mississippi Valley. From his headquarters in Louisville, Kentucky, Allen supervised the Federal supplies for all the region's major campaigns, including Vicksburg and Atlanta. He was able to secure a wide variety of surplus railcars from various Northern railroads and arranged to have them ferried across the Ohio River from Jeffersonville, Indiana, and used for military purposes to transport food and supplies to the field armies along former Confederate railways.

As a result of his performance, he was promoted to brigadier general and given command all quartermaster operations west of the Mississippi River, except for California. Allen ranked only behind Quartermaster General Montgomery C. Meigs (a fellow USMA 1836 graduate) in terms of responsibility and influence. His efficiency in large scale logistics helped ensure that the Federal armies in his theater of war were much better equipped and fed than their Confederate opponents.

Allen was breveted to major general in both the volunteer army and the Regular Army in the omnibus promotions following the war, to date from March 1865.

After the war, Allen stayed in the Regular Army until his retirement in 1878 as the army's assistant quartermaster general, spending some $111 million during his lengthy career.

Allen died in Europe while traveling, and was buried in Chène-Bougeries Cemetery in Geneva, Switzerland.