On December 25, 1776, 4,000 Americans crossed the Delaware River to march on Trenton, New Jersey. In Trenton, the Americans attacked 1,400 German mercenaries by surprise, while they were wintering. Shortly after the attack, the Germans surrendered.
Britain sent General John Burgoyne with 8,000 troops to take control of New York's Hudson River Valley. The army had to pass through rough terrain and fight many militias along the way. When they reached Saratoga Springs, militia troops surrounded Burgoyne and his men. Burgoyne eventually surrendered and the Americans won. This victory was a major turning point in the revolution.
Washington and his army camped in Valley Forge, Pennsylvania while the British still occupied Philadelphia. During that winter, about 2,500 of Washington's troops died from disease and exposure, but Washington continued training his troops for battle. In June 1778, they attacked the British at Monmouth, New Jersey and won.