Exiting the Great Lakes via the Welland Canal and the St. Lawrence River, Mimosa proceeded by short sailings down the U.S. East Coast.

At the end of the year, with the United States at war, she steamed from Jacksonville, Florida, to bolster the defenses of the high priority Panama Canal.

In January 1944, 1-1⁄2 years after she escaped a torpedo attack, Mimosa showed the effectiveness of the Navy’s antisubmarine program to check the U-boat menace when she assisted in removing the nets along the Costa Rican and Honduran coasts.

Transiting the Panama Canal 21 April 1944, she sailed for the Mariana Islands, arriving 20 June 1944 in the midst of the Battle of Saipan.

On 13 July 1961 she was turned over to the U.S. Maritime Commission at Olympia, Washington and entered the National Defense Reserve Fleet there.