In the Eastern Theater of the American Civil War, the basic offensive plan for the Union had been to advance and seize the Confederate capital, Richmond, Virginia. In the first two years of the war, four major attempts had failed: the first foundered just miles away from Washington, D.C., at the First Battle of Bull Run (First Manassas) in July 1861. Maj. Gen. George B. McClellan's Peninsula Campaign took an amphibious approach, landing his Army of the Potomac on the Virginia Peninsula in the spring of 1862 and coming within 6 miles (9.7 km) of Richmond before being turned back by Gen. Robert E. Lee in the Seven Days Battles. That summer, Maj. Gen. John Pope's Army of Virginia was defeated at the Second Battle of Bull Run. In December 1862, Maj. Gen. Ambrose Burnside commanded the Army of the Potomac and attempted to reach Richmond by way of Fredericksburg, Virginia, where he was defeated at the Battle of Fredericksburg. This string of Union defeats was interrupted in September 1862 when Lee moved into Maryland and his campaign was turned back by McClellan at the Battle of Antietam, but this represented no threat to Richmond.