The Coolidge was occasionally used by the War Department on a part-voyage basis. Her first voyage on a full-time basis for the army began at San Francisco on 15 July 1941 and took her to Honolulu and Manila. After returning in late August the ship again left San Francisco in early September for Honolulu and Manila. On 1 November 1941 the SS President Coolidge once more sailed from the Golden Gate for the same destinations, and was en route home, midway between Manila and Honolulu, when the Japanese attack on Pearl Harbor occurred. She reached San Francisco on Christmas Day 1941.
A site to visit for extensive history of the SS Coolidge: http://www.michaelmcfadyenscuba.info/viewpage.php?page_id=34