The Tricorne.

The cast of Le tricorne - 1972 includes: Pierre Decazes as Un gendarme Yvon Sarray as Le commissaire Henri Virlojeux as Le gouverneur

If you are asking about the American Civil War, there were no Hessian units at all.

In the American War of Independence, they wore blue, Prussian-styled uniforms, and either a tricorne, fusilier cap, or grenadier cap. Hessian riflemen (jeagers) wore green coats instead (with a tricorne)

Tricorne means "having three horns".

The British redcoats usually wore a wierd point in the back, flat in the front hat. Most captains and naval officers wore the tricorne. The tricorne was the main sea hat, the recoats on ground wore different hats to individualze each regiment.