[3][4] Benson was present with Battery A at the battles of Palo Alto, Resaca de la Palma, Monterrey, Vera Cruz, and Churubusco.

He rose to the rank of first sergeant in command of an artillery piece in Duncan's battery under section chief Lieutenant Henry Jackson Hunt at the siege of Mexico City, particularly active at the Battle of Chapultepec at the San Cosmé Garita.

Artillery serving with Batteries D and I, posted variously from New York, South Carolina, Michigan, Kansas, and Texas, as well as extensively throughout Florida.

[8][9][10][11] Arriving at Fort Center in April 1855, Benson noted his surroundings as "more disagreeable, unhealthy and devoid of interest than I had expected….Mosquitos awful.

On August 2, 1856, the unit engaged the Seminoles at Punta Rassa, an action which concluded the regiment's duty in Florida.

By the end of the year, all units were transferred back north, headquartered at Fort Hamilton, New York.

Artillery commanded by Captain Lewis G. Arnold, posted at Fort Independence, Massachusetts; in January 1861, Arnold's command was transferred to the unfinished Fort Jefferson, Florida, in order to aid in the preparation for war following the secession of Florida from the Union.

Hunt was promoted to colonel as the Chief of Artillery for the defenses of Washington, D.C.,[17][18] and Benson was transferred to command of Battery M in September 1861.

[7] In 1862 Battery M moved with the Army of the Potomac into Virginia as part of Major General George B. McClellan's Peninsula Campaign (March–July 1862).

The battery remained in camp during the battles of Beaver Dam Creek/Mechanicsville and Gaines' Mill, and was then deployed to cover the approaches of a bridge over the Chickahominy on June 28 during the V Corps' retreat south of the river; on June 29, the battery moved through the White Oak Swamp and was detailed to an advanced night reconnaissance with Colonel William Averell's 3rd Pennsylvania Cavalry beyond the Glendale crossroad, accompanying Brigadier General George A. McCall's Third Division, V Corps toward Malvern Hill, into the early morning of June 30; the battery moved on to Malvern Hill prior to the Battle of Glendale, but was hotly engaged the following day with the rest of the Horse Artillery Brigade during the Battle of Malvern Hill on July 1.

[4] The Seven Days battles proved disastrous for the Army of the Potomac, and McClellan refused to take further offensive action from his position at the Union camp at Harrison's Landing on the James River without reinforcements.

Benson was mortally wounded during the fire when his leg was broken by a fragment from a burst artillery shell; it was reported to be from one of Battery M's own 3-inch Ordnance rifles.