In the spring of 1861, Charlie, a young man haunted by his father's failures and troubled by a lung damaged from consumption, is working a boring administrative job at an ironworks in Western Maryland. When the Civil War breaks out, he becomes an officer in the Union Army and looks forward to a glorious adventure. He fights at the battle of Antietam and distinguishes himself on the field but is shocked by the immense carnage, a total of 23,000 casualties in a single day.
When he returns home to Massachusetts to lead a new regiment, Charlie meets a young woman and falls in love. He balances the strain of command with this new romance and feels conflicted by his desire to stay home and have a family and the continued pressure to serve a role in the war. He experiences a mutiny in which he shoots and kills one of his own soldiers. With his return to the front pending, and haunted by the killing of his own soldier, Charlie faces a decision between his duty to his wife and his desire to serve his country.