The USS Cyclops (AC-4) was a twin-engine, twin-screw US Navy collier. When launched in 1910, it operated in the Naval Auxiliary Service, which was somewhat similar to the Military Sealift Command. Its homeport was Norfolk, Virginia. The ship’s master was George W. Worley, who bore the rank of Lieutenant Commander, Naval Auxiliary Service. In 1911, Cyclops sailed to the Baltic Sea, providing coal to Second Division ships operating in those waters. For the next few years, it operated along the US East Coast and throughout the Caribbean in support of the US Navy. During the period of troubled relations between the United States and Mexico in 1914-1915, it supported US Navy warships patrolling in the Gulf of Mexico and the Caribbean. After the United States declared war against the Axis Powers, Cyclops was commissioned as a ship of the US Navy and her master, George W. Worley, was commissioned into the Navy and promoted to Commander. In June 1917, the ship joined a convoy en route Saint-Nazaire, France, returning to the US the next month. It then resumed servicing Navy warships along the East Coast. In January 1918, it was assigned to the Naval Overseas Transportation Service and departed for the South Atlantic to service Royal Navy warships in those waters. Ships of the Royal Navy had ships of the Imperial German Navy on 14 December 1914 in the Battle of the Falkland Islands. In February 1918, Cyclops departed Rio de Janeiro for the United States. On board were a number of passengers, including one diplomat and five military prisoners (three Navy sailors and two Marines) headed to the Navy brig at Portsmouth, New Hampshire. The ship stopped in Bahia, Brazil, where it loaded approximately 10,800 tons of manganese ore. Manganese was used as an ingredient in explosives. Commander Worley submitted a report before departing Bahia that the starboard engine had a cracked cylinder and was not operative. On 3 March 1918, Cyclops made an unscheduled stop in Barbados because its waterline was over the Plimsoll mark, indicating the ship was overloaded. It being war time, this was overlooked and the ship departed for Baltimore on 4 March. It was due to arrive on 13 March, but was never seen again. Its loss, with 306 passengers and crew, remains the single largest loss of life in US Navy history not involving combat. The wreck has never been found. During World War II, two of its sister ships were lost in the North Atlantic without a trace while carrying heavy loads of metallic ore. The 1918 sinking must have occurred suddenly, as no distress call was received. It is probable that Cyclops encountered heavy weather and suffered a catastrophic hull failure.