The Maginot Line was arguably the most sophisticated system of fortifications in history. Kilometers thick at points, it had observation posts, anti-tank ditches, fortresses with retractable turrets, flood zones, and thousands of bunkers. Contrary to the way it is often described in history books, it wasn’t irrelevant. It blocked an invasion route through northern France, including and especially Alsace-Lorraine, which France had fought for at great cost. It simply wasn’t as relevant, or relevant in the way its designers intended, after the character of war changed.

War has an unchanging nature. War is violent, interactive, and fundamentally political. War’s character, by contrast, changes, and reflects how technology, law, ethics, and many other factors influence combatants’ use of violence to create political outcomes. The character of war is a semi-regular topic of discussion among military theorists, and one that has an unfortunate tendency to descend into esoteric arguments that are fascinating to a small number of people. But debates over the character of war might be more important than they have been in decades. The evolving nature of information technology and its use by militaries may change the character of war. If and when this takes place, competence in and even mastery of some previous ways of war will become less relevant. Failure to lead the next change to the character of war could result in the U.S. military’s advantages in training, resources, and technology quickly diminishing or disappearing altogether.

Changes to the Character of War in History

The French Revolutionary and Napoleonic Wars saw a shift from limited wars of maneuver by professional armies to decisive battles fought, in many cases, by massive armies driven by nationalism. One of the first indications of this shift took place at the Battle of Valmy. The Prussian army fought a mostly cautious battle,