After the British quit Boston, they slowly adopted a strategy to isolate New England from the rest of the colonies and force the insurgents in that region into submission, believing that doing so would end the conflict. At first, British forces focused on taking the principal colonial centers. They began by easily capturing New York City in 1776. The following year, they took over the American capital of Philadelphia. The larger British effort to isolate New England was implemented in 1777. That effort ultimately failed when the British surrendered a force of over five thousand to the Americans in the fall of 1777 at the Battle of Saratoga.
The major campaigns over the next several years took place in the middle colonies of New York, New Jersey, and Pennsylvania, whose populations were sharply divided between Loyalists and Patriots. Revolutionaries faced many hardships as British superiority on the battlefield became evident and the difficulty of funding the war caused strains.