Napoleon Hat equals crazy?

In many stereotypical cartoons of the 20th century a crazy person is in a strait jacket wearing a Napoleon hat. What is the origin of the hat and does anyone know of the earliest reference?

Bicorne.

Wikipedia has no exact earliest date and I have no idea off the top of my head, but it is interesting that it apparently became popular in various military circles right about the time Napoleon was rising to prominence. Or in other words Napoleon was on the cutting edge of military fashion in his day :).

http://www.quora.com/What-is-the-derivation-of-the-Napoleon-Delusion-cliche

“one crazy corsican is enough for europe.”