On October 28, 1776, at the Battle of White Plains, George Washington was forced to retreat to New Jersey. From the article:
"Battle of White Plains Facts & Summary
New York
October 28, 1776
After American defeats at the Battles of Long Island and Harlem Heights, George Washington moved his army northwards into New York State. The British pursued him doggedly by land and river. By October 28, the Americans had reached their base of supplies at White Plains, New York. They fortified the town with a line of breastworks that some soldiers later claimed was composed primarily of cornstalks.
On the morning of October 28 the British, led by General William Howe and supported by Hessian auxiliaries, moved to attack. A sharp firefight erupted as American skirmishers tried to disrupt the British advance. The skirmishers eventually fell back to Chatterton Hill on the main American line, and held against repeated Hessian assaults. The British advance stalled as the army reformed and prepared another attack. Howe arranged his army for a flank attack, a tactic that had worked again and again against the poorly trained Americans.
The British and Hessians were met by determined musketry as they climbed the slopes of Chatterton Hill. Despite the fierce resistance, however, a Hessian force was able to dislodge the militia that protected the American right flank. The line began to unravel as more Hessians poured into the breakthrough. Washington ordered a fighting withdrawal with the 1st Delaware Regiment guarding the rear.
The Continentals continued their retreat to North Castle, New York. General Howe declined to pursue that far, returning to Manhattan to deal with Fort Washington and Fort Lee.
The Battle of White Plains resulted in roughly 217 American casualties and 233 British casualties. With the defeat at White Plains, and the disaster at Forts Washington and Lee, Washington was forced to abandon New York and retreat across New Jersey. Washington and his men would come roaring back, however, in December of 1776 at the Battle of Trenton."