Nicholas passed as a midshipman July 1, 1842, and was assigned to the frigate USS Columbus in the Mediterranean Squadron serving until 1844.

With the outbreak of the Civil War, Nichols remained loyal to the United States and was given command of the steamer USS Winona in the West Gulf Blockading Squadron.

He was then present with the 38-vessel flotilla commanded by Rear Admiral David Farragut during the attack on and passing of the batteries at Vicksburg, Mississippi, on June 28, 1862.

With the USS Mendota, Nichols saw heavy action when he engaged a rebel battery at Four Mile Creek on the James River, June 16, 1864.

He served as member of the Navy's Board of Examiners in 1877 and commissioned rear admiral February 25, 1878, commanding the South Atlantic Squadron until 1879.

He died October 12, 1886, and is buried with his wife and children at Swan Point Cemetery, Providence, Rhode Island.