The Somers was laid down at the Brooklyn Navy Yard in early 1842 and commissioned on 12 May. On 13 September, after a shakedown cruise that summer under Commander Alexander Slidell Mackenzie, she sailed as an experimental school ship for naval apprentices to Africa with dispatches for the U.S. sloop Vandalia. With no luck finding the ship, Mackenzie learned on 10 November in Monrovia, Liberia, that the Vandalia had sailed for home. The Somers set sail for the Virgin Islands in hopes of intercepting the sloop there.
While nearing St. Thomas on 26 November, Lieutenant Guert Gansevoort reported to Mackenzie that he had learned of a plot to murder the officers and most of the crew and turn the Somers into a pirate ship. Gansevoort named Acting Midshipman Philip Spencer, the son of Secretary of War John Canfield Spencer, as the ringleader of the conspiracy. He was arrested the next day, as were Boatswain’s Mate Samuel Cromwell and Seaman Elisha Small.