type of weapon was deployed for coastal defense during the war (an 1862 map shows an external battery of them at Fort Monroe) and more widely deployed following the war. 1862 In March 1862, the naval Battle of Hampton Roads took place off Sewell's Point between two early ironclad warships, CSS Virginia and USS Monitor. While the outcome was inconclusive, the battle marked a change in naval warfare and the end to wooden fighting ships. Later that spring, the continuing presence of the Union Navy based at Fort Monroe enabled federal water transports from Washington, D.C., to land unmolested to support Major General George B. McClellan's Peninsula Campaign. Formed at Fort Monroe, McClellan's troops moved up the Virginia Peninsula during the spring of 1862, reaching within a few miles of the gates of Richmond about 80 miles to the west by June 1. For the next 30 days, they laid siege to Richmond. Then, during the Seven Days Battles, McClellan fell back to the James River well below Richmond, ending the campaign. Fortunately for McClellan, during this time, Union troops regained control of Norfolk, Hampton Roads, and the James River below Drewry's Bluff (a strategic point about 8 miles south of Richmond). Beginning in 1862 Fort Monroe was also used as a transfer point for mail exchange. Mail sent from states in the Confederacy addressed to locations in the Union had to be sent by flag-of-truce and could only pass through at Fort Monroe where the mail was opened, inspected, resealed, marked and sent on. Prisoner of war mail from Union soldiers in Confederate prisons was required to be passed through this point for inspection. 1864–1867 In 1864, the Union Army of the James under Major General Benjamin Butler was formed at Fort Monroe. The 2nd Regiment, United States Colored Cavalry, mustered in at Fort Monroe on December 22, 1864, and the 1st Regiment, United States Colored Cavalry mustered in the same day at nearby Camp Hamilton. The Siege of Petersburg during 1864 and 1865 was supported on the James River from a base at City Point (now Hopewell, Virginia). Maintaining the control of Hampton Roads at Fort Monroe and Fort Wool was crucial to the naval support Grant required for the successful Union campaign to take Petersburg, which was the key to the fall of the Confederate capital at Richmond. As Petersburg fell, Richmond was evacuated in 1865 on