Before the Battle of Antietam, McClellan's plan primarily involved gathering more intelligence on Confederate movements.

After the Battle of South Mountain, he sought to understand the size and position of General Lee's army, which was crucial for planning his next moves. Although he had the objective to confront Lee directly, McClellan was known for his cautious approach, often prioritizing reconnaissance over immediate engagement. This focus on intelligence gathering ultimately delayed decisive action, impacting the battle's outcome and the broader campaign against the Confederacy.