USS Thrush (AM-18) was a Lapwing-class minesweeper acquired by the United States Navy for the dangerous task of removing mines from minefields laid in the water to prevent ships from passing.

Engaging in peacetime exercises and maneuvers in the Hawaiian Islands into the early spring of 1922, the minesweeper was decommissioned at Pearl Harbor on 3 April and placed on the inactive list.

Operating with Aircraft Scouting Force through 1939, the seaplane tender was attached to PatWing 5 tending a brood of planes at San Juan, Puerto Rico, when World War II began in Europe.

Anchoring off the mouth of the St. Johns River, near Jacksonville, Florida, Thrush stood plane-guard duty while tending a covey of Martin PBM Mariners through January and February 1941.

Switched to Tucker's Island, near Hamilton, Bermuda, Thrush continued her plane-tending duties through March, on occasion serving as a small cargo vessel to transport supplies from ships to docks and depots on shore.

The seaplane tender then performed similar duties at San Juan, Puerto Rico, and in the British West Indies until she departed Trinidad on 28 November, bound for Brazil.

She arrived at Pará on 7 December 1941, the day Japanese planes swept down on the American base at Pearl Harbor in a devastating raid which plunged the United States into World War II.

Refuelling planes, carrying supplies, and serving as a seagoing "jack-of-all-trades" – even as a floating radio station upon occasion – Thrush continued operations off the Brazilian coast through the early spring of 1942.

Arriving at Hampton Roads on 1 November, the ship underwent an overhaul and upkeep period at the Norfolk Navy Yard before 12 days of gunnery training and other exercises in Chesapeake Bay through 26 December.

She transited the Panama Canal and called at Manzanillo, Colima, Mexico, and San Diego, en route, and reached Pearl Harbor on 26 August.