Napoleon's military success stemmed not from inventing new ways of war, but from mastering the available tools and concepts of his era to a degree his opponents had not. This historical lesson serves as a warning for the modern US, whose slow adaptation to existing threats like drones suggests it is failing to master the current military landscape.

The influential theory that only 10% of WWII soldiers fired their weapons at the enemy, proposed by S.L.A. Marshall, has been debunked as based on falsified interviews. Despite its inaccuracy, the theory significantly changed military training to include conditioning soldiers to shoot at human-shaped targets.

Despite new technologies, the Civil War's generalship resembled the Napoleonic era more than WWI. Command was dominated by individual personalities and singular decisions, like Pickett's Charge, rather than the vast, impersonal, and bureaucratized military machines that would define 20th-century warfare.

Despite becoming an icon of the war's horror, poison gas was a tactical failure. It was unreliable due to wind and failed to cause mass casualties, killing only 6,000 British and Imperial forces throughout the war. Its primary impact was terror, not breaking the trench deadlock.

Military technology often evolves incrementally. However, a breakthrough like the Maxim machine gun can suddenly render centuries of established doctrine—such as the drilled infantry charge—completely obsolete. This creates a strategic crisis that forces an equally radical technological and tactical response, like the tank.

The narrative of incompetent generals is too simplistic. They faced a novel military challenge—defensive technology like machine guns and trenches massively outpaced offensive tactics. Their deadly "experiments" were desperate attempts to solve a problem with no known answer, not just callousness.

New military technologies like iron weapons or hoplite shields didn't instantly revolutionize ancient warfare. Their impact was gradual and contingent on broader societal developments, such as increased wealth and larger cities, which enabled their widespread use in new tactical formations.

Promotion was based almost entirely on time in service, not merit. This led to absurd situations where a proven general like George Meade was technically junior to the less competent Ambrose Burnside because of their commission dates, forcing convoluted command arrangements during critical campaigns.

Contrary to expectations of a high-tech war, the conflict in Ukraine demonstrates enduring principles of warfare. The superiority of defense over offense, the difficulty of breakthroughs without air power, and the tendency toward attrition are all classic lessons that would be recognizable to strategists from past major conflicts.