Ormsby, APA-49, was the lead ship of her class of attack transports. Moore Dry Dock at Oakland laid her down on 21 July 1942 as the merchant ship Twilight, a C2 hull, Maritime Commission hull 288. She was assigned to the Navy as the transport Ormsby (AP-94) on 5 October 1942, launched on 20 October 1942, became APA-49 on 1 February 1943, was acquired on 10 March 1943, and was commissioned on 28 June 1943, Captain Leonard Frisco, USNR, in command. She was named for a county in Nevada.
She landed her troops at Tarawa on 20 November 1943 and at Kwajalein on 31 January 1944. She then went to Guadalcanal and trained Army units, landed reinforcements at Bougainville on 28 March, and put Army assault troops ashore at Aitape, New Guinea, on 23 April. She landed the 1st Provisional Marine Brigade at Guam on 21 July 1944. There she suffered her only casualties of the war, when a shell hit her bow and killed an officer and an enlisted man. NavSource lists two Purple Hearts for the deaths on 21 July. She then landed the 1st Marine Division on Peleliu and made the Leyte assault on 20 October, with a second trip on 14 November.
After a California overhaul she carried Seabees to Guam, where she arrived on 11 April 1945, and made Magic Carpet runs for returning veterans. She reached Tokyo on 13 September 1945 with the 43rd Division and then ran occupation missions to Qingdao and to Haiphong and Formosa, where she landed the 62nd Chinese Army at Port Saei on 18 November.
She was decommissioned on 15 March 1946 and struck on 17 April 1946. She was delivered to the War Shipping Administration on 16 May 1946, sold to United States Lines and renamed American Producer. In March 1969 she struck a pier at San Francisco outbound for Da Nang with a cargo of bombs and was badly damaged. DANFS says she was scrapped at Kaohsiung in July 1969, and NavSource gives a sale for scrapping to Mitsui on 22 May 1969. She earned six battle stars.