In the novel, some Confederate prisoners are killed in the Northwest Bastion. The killings are supported in the historical record by one cryptic sentence in Lieutenant Benjamin’s after-action report to General Burnside. The lieutenant, in describing the zeal of the defenders, wrote that “One man used an axe.”

Such behavior was not unknown in the war in which hatred on both sides was intense. But it ran against a new code of conduct that had been issued seven months earlier by Gen. Henry W. Halleck, the very unpopular commander in chief of the army.

His General Order No. 100 “provided a code of conduct for Federal soldiers and officers when dealing with Confederate prisoners and civilians. The code was borrowed by many European nations, and its influence can be seen on the Geneva Convention.”

Via Lint In My Pocket–Artillery On The Ridge