Why was McClellan removed after the battle of Antietam?

General George McClellan was removed from command after the Battle of Antietam primarily due to President Abraham Lincoln's frustration with McClellan's cautious approach and failure to pursue the Confederate Army after the battle. Although Antietam was a strategic victory for the Union, McClellan's reluctance to capitalize on the weakened state of General Robert E. Lee's forces prompted Lincoln to seek a more aggressive commander. Ultimately, McClellan's inability to decisively engage the enemy and achieve further victories led to his dismissal in November 1862.