The irony of the title
An angel is typically understood through the lens of mythic lightness, wearing white and floating ethereally, harp in hand. But this title, like the novel, stages a different understanding of Angels. The killers in the book are the soldiers themselves, which makes this irony deeply symbolic. By titling the novel The Killer Angels, the novelist underscores the tragic nature of these battles, and it raises the stakes to a supernatural, mythic level.
The irony of attack
When they seem out of resources, the Confederate army and the Union army both have the question to ask. Do they spare their army by retreating, knowing the likely outcome will be that their enemy takes advantage of them, or do they attack? Ironically, they must attack in order to defend, because to attack is to send a message to the enemy that they are more powerful than they really are. To allow the enemy to understand when they are weak might just be losing the war.
The irony of a single moment
Although the scope of war demands a broad awareness of strategy and timing, the specific moments of the war comprise the war, so every single moment is to be considered the most important moment of their entire lives. The leaders must never let their guard down, and this drains them of their resolve, but they must endure the personal horror enough to keep their mind's clear so they can address each moment's unique problems.
The irony of spies and intel
The war functions of intelligence from spies, but without the right intelligence, the spies are essentially useless. The spies are ironic because they are the opposite of combat power. Instead of waiting until the right moment to attack, they seek to infiltrate the enemy when they are powerless to affect anything. Their job is to observe, to gain knowledge, and to bring their research back to the people in power. They are facing the whole enemy alone, knowing that their capture means certain death.
The irony of Confederate failure
In the novel, the story of the Confederate loss at Gettysburg is depicted ironically, showing the reasons why the South believed their plans would work, but then, instead of seeing the results they predicted, they walk right into cannon fire, and their incisive maneuvers lead to utter decimation. They lose the war based on their strategy. The units lose over half of their forces, and the war changes direction, pointing to the Union's inevitable victory.
