I think many generals aren't rational, otherwise they would have put their leadership qualities into being a building site supervisor or a teacher instead of into persuading lots of people to run around shooting other people.

I wish I had your faith in the essentially benevolent nature of reason. The way I see it, reason is just a tool for enabling one to best attempt to achieve one's goals, and to a large extent the nature of the goals is independent of the quality of the reason used to try to achieve them. So someone can have goals that are selfish, narrow-minded, short-sighted or outright evil while still being reasonable.

It would be very nice if that weren't the case: if everyone who had crappy goals was also sufficiently unreasonable to be bad at finding ways to achieve them. Unfortunately, I don't believe that :-/