The ship was built as the cargo vessel Cavalier for the Philadelphia and Norfolk Steamship Company by Pusey and Jones Corporation, Wilmington, Delaware in 1938.

In 1952 the ship became Monte de la Esperanza for a company in Bilbao, Spain transporting bananas to the United Kingdom from the Canary Islands for more than 20 years.

[3][7] The ship was converted at the Bethlehem Steel Co., Atlantic Works, East Boston, Massachusetts; and commissioned as the Coastal Minelayer Monadnock (CMc-4), 2 December 1941.

[3] In the spring of 1943, Monadnock operated off the southern New England coast, first for the Minecraft Training Command and then under ComServFor, Atlantic Fleet, before resuming maneuvers in Chesapeake Bay.

Reassigned to the Pacific Fleet in late fall, the minelayer departed Norfolk, Virginia, with TG 29.18, transited the Panama Canal and arrived at San Diego 28 December.

Operating again in the New Hebrides, based at Espiritu Santo, by October, she sailed, with passengers, to Brisbane, and upon her return replenished her stores and departed, 13 November, for Manus, Admiralty Islands, to join the 7th Fleet.

Then, in convoy with TU 51.29.18, she departed for the United States, arriving at San Francisco, 24 June, for overhaul and conversion to Auxiliary Mine Layer ACM-10 (effective 10 July 1945).

[3] The ship remained in the reserve fleet until sold for $104,000 17 June 1947 to James J. Wilkinson for operation with signal WNOQ and home port of Norfolk, Virginia.