text: Both sides suffered heavy casualties. Lee's Army of Northern Virginia suffered about 20,000 casualties (3,494 killed, 15,758 wounded, and 952 captured or missing) out of a total of over 90,000 soldiers during the Seven Days. McClellan reported casualties of about 16,000 (1,734 killed, 8,062 wounded, and 6,053 captured or missing) out of a total of 105,445. Despite their victory, many Confederates were stunned by the losses. The number of casualties in the Seven Days Battles surpassed the total number of casualties in the Western Theater of the war until that point in the year.
  The effects of the Seven Days Battles were widespread. After a successful start on the Peninsula, which foretold an early end to the war, Northern morale was crushed by McClellan's retreat. Despite heavy casualties, which the less populated South could ill afford, and clumsy tactical performances by Lee and his generals, Confederate morale skyrocketed, and Lee was emboldened to continue his aggressive strategy through the Second Battle of Bull Run and the Maryland Campaign. McClellan's previous position as general-in-chief of all the Union armies, which had been vacant since March, was filled on July 23, 1862, by Major General Henry W. Halleck, but McClellan retained command of the Army of the Potomac. Meanwhile, Robert E. Lee embarked on a thorough reorganization of the Army of Northern Virginia by forming it into two corps, commanded by James Longstreet and Stonewall Jackson. Lee also removed several generals, such as John Magruder and Benjamin Huger, who had performed poorly during the Seven Days Battles.