After a series of stunning victories, Robert E. Lee’s Army of Northern Virginia invaded Maryland in September 1862, hoping to score both victories in battle and propaganda victories that might help the Confederacy earn international recognition. Instead, a copy of Lee’s marching orders made it to the Army of the Potomac, spurring General George B. McClellan to move his army at a pace faster than Lee anticipated. Lee gave battle on September 17, turning the battle into the bloodiest single day of the war, and his army barely escaped destruction.Despite heavily outnumbering the Southern army and badly damaging it during the battle, McClellan declined to pursue Lee across the Potomac, citing shortages of equipment and the fear of overextending his forces. General-in-Chief Henry W. Halleck wrote in his official report, "The long inactivity of so large an army in the face of a defeated foe, and during the most favorable season for rapid movements and a vigorous campaign, was a matter of great disappointment and regret." Lincoln relieved McClellan of his command of the Army of the Potomac on November 7, effectively ending the general's military career.The correspondence between General McClellan and officials in the Administration, including Secretary of War Edwin Stanton and General-in-chief Henry Halleck, in which the officials try to piece together the reasons for McClellan’s delay, was preserved as part of The War of the Rebellion: Official Records of the Union and Confederate Armies. This edition of the Official Records includes the correspondence and pictures McClellan, Lincoln, Stanton, Halleck, the battlefield and more.