Appointed midshipman in 1847, he served in the East Indies Squadron on board the sloop of war Plymouth in 1847 and 1848 and on board the brig Dolphin in 1849 and 1850. In the latter warship, he participated in the capture of a pirate Chinese junk near Macao, China. During this action, he received a pike wound in the thigh. After another tour of duty in Plymouth followed by one in the frigate Saranac, Benham attended the Naval Academy in 1852 and early 1853.
On 10 June 1853, he was promoted to passed midshipman. From mid 1853 to early 1857, he served in the sloop of war St. Mary's on the Pacific Station. On 16 September 1855, while still in St St. Mary's, Benham was commissioned a lieutenant. He next served a tour of duty with the Coast Survey late in 1857 and early in 1858. Later that year, he was transferred to the steamer Western Port assigned to the expedition sent to Paraguay to extract an apology for shooting at the gunboat Water Witch. In 1860, he moved to the steamer Crusader in the Home Squadron.
After the Civil War broke out, Lt. Benham served on board the steamer Bienville in the South Atlantic Blockading Squadron and, in her, took part in the capture of Port Royal, S.C., on 7 November 1861. On the date that rank was established, 16 JuIy 1862, Benham was promoted to lieutenant commander. Following brief service in Sacramento in 1863, he assumed command of the gunboat Penobscot and served in her through the end of the Civil War, patrolling the Texas coast as part of the West Gulf Blockading Squadron.
Upon the return of peace, he served at the New York Navy Yard from 1866 to 1870, but for a stint of duty in Susquehanna in 1867. Following duty as a lighthouse inspector in 1870 and 1871, Benham commanded first Canonicus and then Saugus, both on the North Atlantic Station and returned to lighthouse inspecting in 1874. After commanding Richmond on the Asiatic Station between 1878 and 1881, he went to the Portsmouth (N.H.) Navy Yard. The years 1885 and 1886 brought him his third tour of duty as lighthouse inspector. Following a tour of duty at League Island, Pa., in 1888, he became commandant of the Mare Island Navy Yard in 1889.
While there he became Rear Admiral Benham in February 1890 and continued at that post until June of 1891. At the end of a year waiting for orders, he assumed command of the South Atlantic Station in June 1892. However, Rear Admiral Benham was soon transferred to command the North Atlantic Station, flying his flag in San Francisco (Cruiser No. 1). When Admiral Custodio de Mello launched his naval revolt in Rio de Janeiro in late 1893, Rear Admiral Benham commanded the American naval units sent there to protect American citizens and interests. Retired from the Navy on 10 April 1894, Rear Admiral Benham died on 11 August 1905 at Lake Mahopac, N.Y.