United States George Washington Nathanael Greene Benjamin Lincoln Lord Stirling John Sullivan Anthony Wayne Marquis de Lafayette Henry Knox Sir William Howe Sir Henry Clinton Lord Cornwallis Charles Grey The Philadelphia campaign (1777–1778) was a British military campaign during the American Revolutionary War designed to gain control of Philadelphia, the Revolutionary-era capital where the Second Continental Congress convened, formed the Continental Army, and appointed George Washington as its commander in 1775, and later authored and unanimously adopted the Declaration of Independence the following year, on July 4, 1776, which formalized and escalated the war.

In the Philadelphia campaign, British General William Howe failed to draw the Continental Army under George Washington into a battle in North Jersey.

Following William Howe's capture of New York City and George Washington's success in the Battles of Trenton and Princeton, the two armies settled into an uneasy stalemate in the winter months of early 1777.

[4] Howe decided in early April 1777 against taking the British Army over land to Philadelphia through New Jersey since this route would entail having to cross of the broad Delaware River under hostile conditions and likely require the transportation or construction of necessary watercraft.

[6] Washington at the time and historians ever since have wondered why Howe was not in place to come to the relief of Burgoyne, whose invasion army from Canada was surrounded and captured by the Americans in October.

[9] After the setbacks in New Jersey, Howe in mid-January 1777 proposed operations against Philadelphia that included an overland expedition and a sea-based attack, thinking this might lead to a decisive victory over the Continental Army.

[10] This plan was developed to the extent that in April Howe's army was seen constructing pontoon bridges; Washington, lodged in his winter quarters at Morristown, New Jersey, thought they were for eventual use on the Delaware River.

Washington's Continental Army had been encamped primarily at Morristown, New Jersey, although there was a forward base at Bound Brook, only a few miles from the nearest British outposts.

In part as a retaliatory measure against the ongoing skirmishes, General Charles Cornwallis executed a raid against that position in April 1777, in which he very nearly captured the outpost's commander, Benjamin Lincoln.

In response to this raid, Washington moved his army forward to a strongly fortified position at Middlebrook in the Watchung Mountains that commanded likely British land routes toward Philadelphia.

Uncertain of Howe's goal, which could be Charleston, South Carolina, he considered moving north to assist in the defense of the Hudson, when he learned that the fleet had entered the Chesapeake Bay.

General Howe landed 15,000 troops in late August at the northern end of the Chesapeake Bay, about 55 miles (90 km) southwest of Philadelphia.

General Washington positioned 11,000 men between Howe and Philadelphia but was outflanked and driven back at the Battle of Brandywine on September 11, 1777, and suffered over 1,000 casualties, and the British lost about half that number.

British and Revolutionary forces maneuvered around each other west of Philadelphia for the next several days, clashing in minor encounters such as the abortive Battle of the Clouds and the so-called "Paoli Massacre."

On October 2, the British captured Fort Billingsport, on the Delaware in New Jersey, to clear a line of chevaux de frise obstacles in the river.

However, the army eventually emerged from Valley Forge in good order, thanks in part to a training program supervised by Baron von Steuben.

The British sent out a peace commission headed by the Earl of Carlisle, whose offers, which were made in June 1778 as Clinton was preparing to abandon Philadelphia, were rejected by the Second Continental Congress.

Clinton shipped many Loyalists and most of his heavy equipment by sea to New York, and evacuated Philadelphia on June 18, after 266 days of British occupation.

Under orders from London, Clinton reallocated some of his troops to the West Indies, and began a program of coastal raiding from Chesapeake Bay to Massachusetts.