In early 1776, King George III of England hired units from the various houses or states of Germany to assist with bringing the the colonist's rebellion to order. The hiring of foreign troops to supplement a country's army was a normal procedure during this time of history. Several of the German rulers, needing hard currency and being "between wars", were only too happy to oblige.
They were Frederick II, Landgrave of Hesse-Kassel (a principality in northern Hesse) King George III's brother in law,his son William, count of Hesse-Hanau and nephew to King George III; Charles I, Duke of Brunswick; Frederick, Prince of Waldeck; Charles Alexander, Margrave of Anspach-Bayreuth; and Frederick Augustus, Prince of Anhalt-Zerbst.
About 18,000 Hessian troops arrived in North America in 1776, with more coming in later, of this about3/4 of them were from Hesse-Kassel. Thus the colonist's newspapers referred to all of them as Hessians and the name stuck.
In addition to firepower, American rebels used propaganda against Hessians. They enticed Hessians to desert to join the German-American population. In April 1778, one letter promised 50 acres (0.2 km²) of land to every deserter. Benjamin Franklin wrote an article that claimed that a Hessian commander wanted more of his soldiers dead so that he could be better compensated.
After the war ended in 1783, 17,313 Hessians returned to their homelands. Of the 12,526 who did not, about 7,700 died - around 1,200 were killed in action and 6,354 died from illness or accidents. Approximately 5,000 Hessians settled in North America, both in the United States and Canada - some because their commanders refused to take them back to Germany because they were criminals or physically unfit. Most of them married and settled among the population of the newly formed United States. Many of them became farmers or craftsmen. The number of their direct descendants living in the U.S. and Canada today is still being debated.