The USS Manhattan was a Canonicus-class monitor built for the Union Navy during the American Civil War, launched on October 14, 1863, and commissioned on June 6, 1864. It measured 223 feet in length overall with a beam of 43 feet 4 inches, and a maximum draft of 13 feet 6 inches. The vessel displaced approximately 2,100 long tons and had a tonnage of 1,034 tons burthen. Her crew numbered around 100 officers and enlisted men. Power was provided by a two-cylinder horizontal vibrating-lever steam engine, developing 320 indicated horsepower, driving a single propeller and reaching speeds up to 8 knots. The ship carried 140–150 long tons of coal and was fueled by two horizontal fire-tube boilers. Her armament consisted of two massive 15-inch Dahlgren smoothbore muzzle-loading guns mounted in a single turret, each weighing about 43,000 pounds and capable of firing shells weighing 350 pounds up to 2,100 yards. The vessel's armor included five layers of 1-inch wrought iron plates on the sides, backed by wood, with the turret and pilot house protected by ten layers of 1-inch plates. The deck was armored with 1.5-inch steel, and additional protection included a soft iron band around the turret's base and armor shielding around the funnel base. Constructed at Joseph Colwell's Jersey City shipyard, the Manhattan's design was modified during construction to increase armor thickness and improve buoyancy and stability. After commissioning, she participated in key Civil War operations, notably at the Battle of Mobile Bay, where she engaged Fort Morgan and the Confederate ironclad Tennessee. During the battle, she fired 11 shots, claiming hits that damaged the Tennessee's steering chains and other components, and was instrumental in the Union victory. The ship also received the surrender of the Tennessee after the battle, although that captain intended to surrender to a different vessel. Following the war, Manhattan saw various service assignments, including patrols along the U.S. coast and Red River, until she was laid up in 1865. She was renamed Neptune briefly in 1869, then reverted to Manhattan. She underwent refits in the early 1870s, was recommissioned, and continued patrols until she was finally laid up at League Island in Philadelphia in 1888. The USS Manhattan was struck from the Navy List in December 1901 and sold for scrap in March 1902, marking the end of her maritime service.

This description has been generated using GPT-4.1-NANO based on the Vessel's wikidata information and then modified by ShipIndex.org staff.