Hat: Pickelhaube

A spiked helmet.

It is most closely associated with the Prussian military.

The Pickelhaube is a spiked helmet worn in the 19th and 20th century by German military, firefighters, and police.

This isn't true, but, soldiers used to stick sausages on the spike so they could cook their lunch while ducking-and-covering, during aerial fire bombings.