One of the reasons McClellan was hesitant in battle was his fear of casualties.

General George McClellan was known for his cautious approach to military engagements, often prioritizing the preservation of his troops over aggressive tactics. This mindset stemmed from his belief that the lives of soldiers were paramount and influenced his decision-making during the Battle of Antietam. His reluctance to fully commit forces and capitalize on opportunities to attack resulted in missed chances to potentially rout the Confederate army. This hesitance ultimately frustrated political leaders and contributed to his removal from command later in the war.