[1] Closson was initially assigned to the 1st Artillery Regiment and performed frontier duty at Fort Yuma, California, from 1854 to 1855.

[1] He took part in the defense of Fort Pickens, Florida from May 1861 to May 1862, including response to Confederate attacks on November 22 and 23, 1861, January 1, 1862, and May 8, 1862.

[1] Closson received promotion to brevet major to date from July 8, 1863, in recognition of his gallant conduct during the capture of Port Hudson.

[1] After a leave of absence, Closson served as XIX Corps chief of artillery from October 1863 to July 1864.

[1] He was promoted to brevet lieutenant colonel to date from August 23 in recognition of his meritorious and gallant conduct at Fort Morgan.

[1] After another leave of absence, Closson served as chief of artillery and cavalry ordnance for the Middle Military Division from November 1 to December 31, 1864.

[1] In addition, he served as a member of the board of visitors for the artillery school at Fort Monroe, Virginia.

[1] Closson authored numerous articles for professional journals and other publications during his career and in retirement.

A partial list includes: In June 1896, Closson left the Army because he had reached the mandatory retirement age of 64.

[1][5] Closson qualified under these criteria, and was advanced to brigadier general with an effective date of April 4, 1904.

[7] Closson was fluent in Latin, Greek, and Hebrew, and collected more than 10,000 books, including rare volumes and first editions.

[2][13] Closson's daughter Ellen was the wife of Brigadier General Henry Howard Whitney.