In the eighteenth century, militaries typically fought only in the summer months. On December 25 and 26, 1776, Washington triumphed over the Hessians encamped at Trenton by surprising them as they celebrated Christmas. Shortly thereafter, he used this same tactic to achieve victory at the Battle of Princeton.
The British southern strategy was to move the military theater to the southern colonies where there were more Loyalist colonists. Slaves and Indian allies, the British hoped, would also swell their ranks. This strategy worked at first, allowing the British to take Charleston. However, British fortunes changed after Nathanael Greene took command of the southern Continental Army and scored decisive victories at the battles of Cowpens and Guilford. This set the stage for the final American victory at Yorktown, Virginia. The southern strategy had failed.