Designed by Charles B. Brodie for use in the Mediterranean Squadron, the Sloop-of-War Saint Mary's was laid down in 1843 at the Washington Navy Yard. She was launched on November 24, 1844 and received a commission from the U.S. Navy on December 13th of the same year. However, by the time her construction was finished she was needed in the Gulf of Mexico where she served as a diplomat and troop transport before engaging in the hostilities of the Mexican War.
A speedy design, St. Mary's was 958 tons with dimensions of 149'4" length, a beam of 37'4" and a maximum draft of 17 feet. The compliment size varied in the sources from 195 to 210. She displaced 1,025 tons, held 5 to 18 tons of ballast, stocked 25,000 gallons of water, and could hold provisions for six months. Her armament varied over time but the register of ships shows her as having sixteen 4 to 8 inch guns that lobbed 18 to 32 pound munitions, plus additional guns accounting her to a 20-gun first-class sloop. Her initial cost to build was $192,113 and around this time St. Mary's cost about $180,000 to provision and operate.
Most of St. Mary's career in the U.S. Navy was spent in the Pacific Squadron where she engaged in gunboat diplomacy in Panama and Nicaragua before the U.S. Civil War (1861-1865). During the Civil War she served as the chief representative of Union Naval forces. After the war, St. Mary's had one last major cruise in the Pacific going to most major ports including New Zealand and Australia. In 1874 at the request of the governor of New York, the U.S. Navy transferred St. Mary's to serve as the school ship for the new nautical school based in New York City. Beginning her duties in 1875, this historic ship served the school that would eventually become SUNY Maritime College until 1908 when she was sold to Thomas Butler and Co., beached, and destroyed for scrap.