When Virginia seceded in April 1861, many of the vessels, guns and repair facilities of the U. S. Navy at the Gosport Naval Yard in Portsmouth were hastily scuttled, destroyed or left behind for the new Confederate government to use. This included the steam frigate USS Merrimack, which had been sunk pierside and her upper works destroyed by fire. The Confederates raised the ship, moved her into the graving dock, and replaced her wooden superstructure with an iron-covered citadel mounting 10 guns. By early March 1862, the new CSS Virginia was ready to engage the Union fleet stationed in Hampton Roads near Fortress Monroe. On March 8th, Virginia steamed down the Elizabeth River into the roadstead where she sank USS Cumberland and ran USS Congress aground and set her afire. The Virginia retired, intending to sink the USS Minnesota and other ships the next day. That evening, the new Union ironclad USS Monitor arrived to protect the wooden fleet. The Monitor mounted only two guns but they were placed inside a revolutionary revolving turret. The next morning, Monitor and Virginia met and initiated the first engagement of ironclads in history. The two ships fought each other to a standstill but the Virginia retired, unable to inflict serious damage on the Monitor. Both sides claimed victory, but the continued presence of the Monitor neutralized the threat of the Virginia to the fleet. Both sides would continue to develop and perfect new ironclad designs during the war.