Big Horn is a river in Montana and Wyoming.
(AO-45: dp. 4,150; l. 426'4"; b. 64'2; dr. 27'9"; s. 12.5 k.; cpl. 239; a. 2 3")
Big Horn (AO-45) was built in 1936 by Sun Shipbuilding and Dry Dock Co., Chester, Pa., as Gulf Dawn; purchased by the Navy 31 March 1942, converted into a Q-ship by Boston Navy Yard, and commissioned 16 April 1942, Commander J.A. Gainard in command.
Big Horn operated in the eastern North Atlantic as a Q-ship from July 1942 to January 1944 without success. She was transferred to the Coast Guard 17 January 1944 and operated as a weather patrol vessel out of Newfoundland until returned to the Navy 1 February 1945.
Upon her re-acquisition by the Navy, Big Horn was redesignated IX-207 and assigned to Service Force, Pacific Fleet. She arrived at Pearl Harbor 8 April and proceeded to the Southwest Pacific where she served as a shuttle tanker, mainly between Ulithi and the Philippines. She got underway for Japan 28 September 1945 and served as station tanker at Nagoya, Japan (3 October 1945-26 February 1946).
Returning to the United States, she was decommissioned 6 May 1946 in the 8th Naval District and transferred to the Maritime Commission 22 November 1946.