Richard Henry Lee wrote to Landon Carter, "The infamous treaties with Hesse, Brunswick, &c. (of which we have authentic copies) and the Ministerial reply to Graftons motion leave not a doubt but that our enemies are determined upon the absolute conquest and subduction of N. America. It is not choice then, but necessity that calls for Independence, as the only means by which foreign Alliance can be obtained.... You seem to apprehend danger from our being aided by despotic States, but remember that France assisted Holland without injury to the latter."
Hesse, Brunswick, etc.: During the War of American Independence, Britain hired the most mercenaries from Friedrich Wilhelm II, the Landgrave of Hesse-Cassel. The mercenaries became generically known as "Hessians." Hundreds of mercenaries, however, came from other German states, like Brunswick and Hanover.
Congress listed Britain's hiring of foreign mercenaries as one of the grievances compelling the American colonies to declare themselves independent states.
Former Minister Lord Dartmouth's response to Duke of Grafton: In a debate in the House of Lords over a conciliatory resolution by Augustus Henry FitzRoy, 3rd Duke of Grafton, William Legge, the Second Earl of Dartmouth (former minister of American affairs) said Britain should not cease military operations in America "till the Colonies own our legislative sovereignty; and, by the acts of duty and obedience, show such a disposition as will entitle them to the favour and protection of the parent State."
Paul Herbert Smith, ed., Letters of Delegates to Congress, 1774-1789: Vol. 4: May 16-August 14, 1776 (Washington, D.C.: Library of Congress, 1979), 117-118; 92, note 5.