Washington had spent the winter at Valley Forge rebuilding his army and defending his position against political enemies who favored his replacement as commander-in-chief. This included Major General Horatio Gates, whose political alliance with the “Conway Cabal” threatened General Washington’s status as commander-in-chief. In February 1778, the French-American Treaty of Alliance tilted the strategic balance in favor of the Americans, forcing the British to abandon hopes of a military victory and adopt a defensive strategy. Clinton was ordered to evacuate Philadelphia and consolidate his army.The Continental Army shadowed the British as they marched across New Jersey to Sandy Hook, from where the Royal Navy would ferry them to New York.

Washington detached around a third of his army and sent it ahead under the command of Major General Charles Lee, hoping to land a heavy blow on the British without becoming embroiled in a major engagement.The battle began badly for the Americans when Lee botched an attack on the British rearguard at Monmouth Court House. A counter-attack by the main British column forced Lee to retreat until Washington arrived with the main body. Clinton disengaged when he found Washington in an unassailable defensive position and resumed the march to Sandy Hook.

The infantry battle gave way to a two-hour artillery duel, during which Clinton began to disengage. The duel ended when a Continental brigade established artillery on a hill overlooking the British lines, forcing Clinton to withdraw his guns. Washington launched two small-unit attacks on Clinton's infantry as they withdrew, inflicting heavy casualties on the British during the second. An attempt by Washington to probe the British flanks was halted by sunset, and the two armies settled down within one mile (two kilometers) of each other. The British slipped away unnoticed during the night to link up with the baggage train. The rest of the march to Sandy Hook was completed without further incident, and Clinton's army was ferried to New York in early July.