How did Britain use its colonies during the war?

The onset of the Revolution found the colonies with no real naval forces but with a large maritime population and many merchant vessels employed in domestic and foreign trade. That merchant service was familiar not only with the sea but also with warfare. Colonial ships and seamen had taken part in the British naval expeditions against Cartagena, Spain, and Louisburg, Nova Scotia, during the nine years of war between Britain and France from 1754 to 1763. Colonists also had engaged in privateering during the French and Indian War, the American phase of that broader conflict (the European phase of which was known as the Seven Years' War).

The importance of sea power was recognized early. In October 1775 the Continental Congress authorized the creation of the Continental Navy and established the Marine Corps in November. The navy, taking its direction from the naval and marine committees of the Congress, was only occasionally effective. In 1776 it had 27 ships against Britain's 270. By the end of the war, the British total had risen close to 500, and the American total had dwindled to 20. Many of the best seamen available had gone off privateering, and Continental Navy commanders and crews both suffered from a lack of training and discipline.