Speed 15 k
Armament 4 4"
The second Proteus (AC-9) was laid down by the Newport News Shipbuilding and Dry Dock Co., Newport News, Va., 31 October 1911, launched 14 September 1912, sponsored by Miss Lucy Day Martin; and commissioned 9 July 1913 Master Robert J. Easton, Naval Auxiliary Service, in command.
Following fitting out and shakedown, the collier Proteus cleared Norfolk 11 November 1913 on the first of four runs to Vera Cruz to coal battleships and cruisers of the Atlantic Fleet protecting American interests in the waters off Mexico. She completed the last of these runs by October 1914. On 27 December 1914 Proteus stood out of Hampton Roads carrying men, fuel, and stores on the first of four runs to the Asiatic Station. She completed her final run to Philippines 4 August.
Proteus got underway from Norfolk again 25 September with coal, oil, men and stores for ships of the Fleet at Rio de Janeiro and Montevideo, returning to Hampton Roads 26 November. Assigned to NOTS, she operated between Norfolk, Boston, and New York, clearing the latter port 14 July 1918 for the British Isles, returning to Hampton Roads on 19 September. She steamed again 24 December for Brest, France and spent the next 6 months transporting coal from Cardiff and Barry to Brest.
Proteus returned to Norfolk, 6 August 1919, and during the greater part of the next three years cruised from Norfolk to replenish the Fleet in the Caribbean. Retransiting the Panama Canal twice she delivered fuel and stores to Pearl Harbor (28 June-l1 July 1920) and to Callao, Peru (28 January-5 February 1921). Her last supply run to the Caribbean ended at Hampton Roads on 25 April 1923 and she spent the remainder of her career in operations between Norfolk and Melville, R.I. She decommissioned at Norfolk 25 March 1924 and remained inactive until her name was struck from the Navy List 5 December 1940. She was sold 8 March 1941 to Saguenay Terminals Ltd., Ottawa, Ontario.