The Philadelphia campaign (1777–1778) was a British effort in the American Revolutionary War to gain control of Philadelphia, the Revolutionary-era capital where the Second Continental Congress convened and signed the Declaration of Independence, which formalized and escalated the war.

As part of the Philadelphia campaign, British General William Howe, after failing to draw the Continental Army under General George Washington into a battle in North Jersey, embarked his army on transports, and landed them at the northern end of the Chesapeake Bay. From there, he advanced northward toward Philadelphia. Washington prepared defenses against Howe's movements at Brandywine Creek, but was flanked and beaten back in the Battle of Brandywine on September 11, 1777. After further skirmishes and maneuvers, Howe entered and occupied Philadelphia. Washington then unsuccessfully attacked one of Howe's garrisons at Germantown before retreating to Valley Forge for the winter.

Howe's campaign was controversial because, while he succeeded in capturing the American capital of Philadelphia, he proceeded slowly and did not aid the concurrent campaign of John Burgoyne further north, which ended in disaster for the British in the Battles of Saratoga and brought France into the war. Howe resigned during the occupation of Philadelphia and was replaced by his second-in-command, General Sir Henry Clinton. Clinton evacuated Philadelphia and moved his troops back to New York City in 1778, in order to stiffen that city's defenses against a possible combined Franco-American attack. Washington then harried the British Army all the way across New Jersey, and forced a battle at Monmouth Court House that was one of the war's largest battles. At the end of the Philadelphia campaign in 1778, the two armies found themselves in roughly the same strategic positions that they had been in before Howe launched the attack on Philadelphia.