Richard Arnold, descending from an old New England family which included the notorious Benedict, was the son of a Rhode Island governor and United States Congressman. He was born in Providence on April 12, 1828, and was graduated from West Point in 1850. Commissioned into the artillery, Arnold at first performed routine duties—at Key West and San Francisco, on the Northern Pacific Railroad exploration, in Washington Territory, and as aide-de-camp to General John E. Wool. As a captain of the 5th Artillery, he commanded a battery at First Manassas and lost all of his guns while covering the retreat of the panic-stricken Federal volunteers. The following spring he entered the Peninsular campaign as chief of artillery of Franklin's division, but was soon appointed acting inspector general of the VI Corps. With the withdrawal of George B. McClellan's army to Harrison's Landing, Arnold won the brevet of major for services at the battle of Savage's Station. In November, 1862, Arnold was promoted to brigadier general of volunteers and assigned to duty as chief of artillery, Department of the Gulf. He engaged in the siege of Port Hudson, in the ill-fated Red River campaign under N. P. Banks (at one time as a cavalry commander), and in the capture of Fort Morgan in Mobile Bay. Thereafter, his war service was confined to membership on a retirement board for disabled officers. At the end of the war he received the brevets through major general, in both the regular and volunteer service. However, his regular rank was only that of a captain of the 5th Artillery, for his promotion to major did not occur until 1875. He was made lieutenant colonel only five days before his death, which occurred at Governors Island, New York, on November 8, 1882, while he was acting assistant inspector general, Department of the East. He was buried in Swan Point Cemetery, Providence.
Reference: Generals in Blue. Lives of the Union Commanders by Ezra J. Warner. Louisiana State University Press. Baton Rouge.