USS Gloucester was a gunboat in the United States Navy. Formerly J. P. Morgan's yacht Corsair, Gloucester was built in 1891 and acquired by the Navy on 23 April 1898. Gloucester was commissioned on 16 May 1898, with Lieutenant Commander Richard Wainwright in command.
Gloucester served in Cuban waters in 1898 with the North Atlantic Fleet, Blockading Station. Under her far-seeing and brilliant commanding officer, Gloucester made a name for daring starting with her first service in Cuban waters in 1898 with the North Atlantic Fleet, Blockading Station. She participated in the Battle of Santiago de Cuba on 3 July against Cervera's fleet. The victory came with no casualties, which was attributed to "The accuracy and rapidity of her fire, making the proper service of the guns on the Spanish ships impossible."
On 25 July, she entered the harbor before the fleet at Guánica, Puerto Rico, and captured the place for the U.S. Army in what is known as the Puerto Rican Campaign. The skillful handling and gallant fighting of Gloucester excited the admiration of all who witnessed the action, and merited the commendation of the Navy Department.
As the Army was anxious to transfer the place of disembarkation to the harbor of Ponce, the Fleet was directed to proceed to Ponce to reconnoiter; capture all lighters found there; and occupy such positions necessary for holding the port until the arrival of the Army. On 1 August, with assistance from Wasp, Gloucester took possession of Arroyo, and hoisting the U.S. flag, Wainwright held it until arrival of the Army, a day later. Subsequently Gloucester cruised along the Eastern seaboard from New York to Provincetown in the fall of 1898.