Hessian involvement during the the American Revolutionary War, was thanks to Landgrave Frederick II of Hesse-Kassel (a principality in northern Hesse or Hessia) and other German leaders who hired out thousands of conscripted subjects as auxiliaries to Great Britain to fight against the American revolutionaries. About 30,000 of these soldiers were sold into service. They were called Hessians, because 12,992 of the total 30,067 men came from Hesse-Kassel.
Hessians comprised approximately one-quarter of the forces fielded by the British in the American Revolution. They included jäger, hussars, three artillery companies, and four battalions of grenadiers. Most of the infantry were chasseurs (sharpshooters), musketeers, and fusiliers. They were armed mainly with smoothbore muskets, while the Hessian artillery used three-pounder cannon.
About 18,000 Hessian troops arrived in the Thirteen Colonies in 1776, with more coming in later. They first landed at Staten Island on August 15, 1776. Their first engagement was in the Battle of Long Island. The Hessians fought in almost every battle, although after 1777, the British used them mainly as garrison troops. An assortment of Hessians fought in the battles and campaigns in the southern states during 1778–80 (including Guilford Courthouse), and two regiments fought at the Siege of Yorktown in 1781.
The British use of Hessian troops rankled American sentiment, and pushed more loyalists to be in favor of the revolution. The British use of foreign troops to put down the rebellion was seen as insulting, as it treated British subjects no differently than non-British subjects. Pro-British Tories believed that the British nature of Americans should have subjected them to something other than mercenary foes.
After the war ended in 1783, some 17,313 Hessian soldiers returned to their homelands. Of the 12,526 who did not return, about 7,700 had died. Some 1,200 were killed in action and 6,354 died from illness or accidents, mostly the former. Approximately 5,000 Hessians settled in North America, both in the United States and Canada. In some cases, their commanders refused to take them back to Germany because they were criminals or physically unfit. Most of the men married and settled amongst the population of the newly formed United States.
Many became farmers or craftsmen and were able to take advantage of opportunities in the new country. The number of their direct descendants living in the U.S. and Canada today is a subject of debate. One persistent story is that George Custer may have been a Hessian descendant.