In 1862, Confederate earthworks surrounding Yorktown blocked the Union army’s advance westward past the town along the York-Hampton Road. On April 5, 1862, the Army of the Potomac’s 3rd Corps advanced against Yorktown, hoping for a victory to end the Civil War as George Washington’s victory there 81 years earlier had ended the American Revolution, and moving along the same road British forces in 1781 had walked out of Yorktown on to surrender to Washington’s army. Believing that more than 100,000 troops held the massive Confederate defenses, Maj. Gen. George B. McClellan decided to besiege Yorktown. While minor skirmishing and engagements between field batteries occurred almost daily, most Union effort went into building siege works, and by May 3 more heavy artillery was aimed at Yorktown than had ever before been massed in a single spot in world history. That night, Gen. Joseph E. Johnston, who had assumed command of Confederate forces in mid-April, decided his troops could not withstand the coming Union bombardment and withdrew them. On the morning of May 4, the Army of the Potomac took possession of Yorktown and retained control of the area for the rest of the war.