sentences:  Shortly thereafter, Lincoln asked Ambrose Burnside to replace McClellan as commander of the Army of the Potomac, but Burnside, who was close friends with McClellan, declined the post.Pope's forces moved South towards Richmond, and in late August, the Army of Virginia met the Confederate army in the Second Battle of Bull Run, which was another major Union defeat.Following the battle, Lincoln turned to McClellan again, placing him in command of the Army of Virginia as well as the Army of Potomac.