The Battle of Helm’s Deep, Part V: Ladders Are Chaos

They held out for twenty years in the Ottoman siege I think.

Intelligent officers could find a way around some of deviations from the plan, but they might not, because they lack a complete picture of the battle, because they might be not intelligent enough to devise a creative solution at the time, and because there a limits to the possible.

The more ways plan could go wrong, the more probability it would go wrong. The more deviations from the plan, the less probability than officers will be able to overcome them.

And one more thing: at war there is an enemy who will do anything to make life of your troops more difficult. Disrupting communications, disinformation, unexpected attacs and troops placement... there are a lot of ways, so even there is just one prerequisite for a plan to work, there is a good deal of a probability than it would go wrong.

In HPMoR[1] Yudkowski mocked complex plans, and proposed a rule:

> That was when Father had told Draco about the Rule of Three, which was that any plot which required more than three different things to happen would never work in real life.

> Father had further explained that since only a fool would attempt a plot that was as complicated as possible, the real limit was two.

[1] http://www.hpmor.com/chapter/24