Hessians (US: /ˈhɛʃənz/ or UK: /ˈhɛsiənz/) were German soldiers who served as auxiliaries to the British Army in several major wars in the 18th century, most notably in the American Revolutionary War. The term is a synecdoche for all Germans who fought on the British side, since 65% came from the German states of Hesse-Kassel and Hesse-Hanau. Known for their discipline and martial prowess, around 30,000 to 37,000 Hessians fought in the war, comprising approximately 25% of British land forces.
While regarded both contemporaneously and historiographically as mercenaries, Hessians were legally distinguished as auxiliaries: whereas mercenaries served a foreign government on their own accord, auxiliaries were soldiers hired out to a foreign party by their own government, to which they remained in service. Auxiliaries were a major source of income for many small and relatively poor German states, typically serving in wars in which their governments were otherwise neutral. Like most auxiliaries of this period, Hessians were attached to foreign armies as entire units, fighting under their own flags, commanded by their usual officers, and wearing their existing uniforms.