A cape on the Washington coast gave Cape Johnson (AP-172) her name. Consolidated Steel at Wilmington, California, launched her on 20 February 1943 under a Maritime Commission contract. Mrs. A. C. Steward was the sponsor. Los Angeles Shipbuilding and Dry Dock converted her into a troop transport. On 1 June 1944 the Navy placed her in commission and assigned her to the Pacific Fleet. Command went to Commander L. C. Farley, USNR.
Her first four months were spent shifting Army and Marine units among Marianas ports and South Pacific bases. That was redistribution, not a landing. Hollandia, with TF 79, was the report on 31 October 1944. Nine days later a resupply echelon sailed for the Leyte fighting. A heavy air attack on 13 November left her undamaged. Her men went ashore at Samar two days afterward, still as resupply rather than the assault day. Manus was the return, to stage for Lingayen Gulf.
Manus was cleared on 28 December 1944. On 7 January 1945 enemy aircraft hit the convoy as the Japanese opened two days of strikes meant to stop the Luzon landing. Her guns joined the screen that kept the formation covered. On 9 January the troops went ashore at White Beach, the landing itself.
Ulithi and Guam were the training stops before Iwo Jima. The 3d Marines and their cargo were aboard when she sailed. Beginning on the landing day, 19 February 1945, and continuing through 27 March, she stayed offshore, sent the 3d Marines and their cargo onto the beach as the fighting required, and drove off air attacks. When the bitter fighting ashore was finished she embarked men of the 5th Marines and carried them to Pearl Harbor. San Francisco received her on 22 April 1945.
Troops then went from the west coast to Manila. On 16 August she cleared the Philippines for Pearl Harbor. Occupation troops loaded there, and she reached Wakayama, on Honshu, on 27 September. Crossings that brought servicemen home followed. She decommissioned on 25 July 1946, and the next day she went back to the owner she had left. Two battle stars were credited for the war.