Chester, Pennsylvania in the context of "Delaware Valley"

The Philadelphia metropolitan area, also referred to as the Delaware Valley or Greater Philadelphia, is a major metropolitan area in the Northeastern United States that centers on Philadelphia, the sixth-most populous city in the United States. This area spans up to four states: southeastern Pennsylvania, southern New Jersey, northern Delaware, and the northern Eastern Shore of Maryland, though it is sometimes considered a tri-state region if northeastern Maryland is excluded. With a core metropolitan statistical area population of 6.245 million residents and a combined statistical area population of 7.379 million as of the 2020 census, it is the ninth-largest metropolitan area in the United States in 2024 and the 68th-largest metropolitan region in the world.

In addition to Philadelphia, other major population centers in the Philadelphia metro area include Reading, Upper Darby Township, and Chester in Pennsylvania; Atlantic City, Camden, Vineland, and Cherry Hill in South Jersey; and Wilmington and Dover in Delaware. As of 2023, the Philadelphia metro area's gross domestic product (GDP) exceeds US$557 billion, making it the nation's 11th-largest metropolitan economy.

The Battle of Brandywine, also known as the Battle of Brandywine Creek, was fought between the American Continental Army of General George Washington and the British Army of General Sir William Howe on September 11, 1777, as part of the American Revolutionary War (1775–1783). The forces met near Chadds Ford, Pennsylvania. More troops fought at Brandywine than at any other battle of the American Revolution. It was also the second longest single-day battle of the war, after the Battle of Monmouth, with continuous fighting for 11 hours. As Howe moved to take Philadelphia, then the American capital, the British forces routed the Continental Army and forced them to withdraw, first, to the City of Chester, Pennsylvania, and then northeast toward Philadelphia.

Howe's army departed from Sandy Hook, New Jersey, across New York Bay from the occupied town of New York City on the southern tip of Manhattan Island, on July 23, 1777, and landed near present-day Elkton, Maryland, at the point of the "Head of Elk" by the Elk River at the northern end of the Chesapeake Bay, at the southern mouth of the Susquehanna River. Marching north, the British Army brushed aside American light forces in a few skirmishes. General Washington offered battle with his army posted behind Brandywine Creek, off the Christina River. While part of his army demonstrated in front of Chadds Ford, Howe took the bulk of his troops on a long march that crossed the Brandywine far beyond Washington's right flank. Due to poor scouting, the Americans did not detect Howe's column until it reached a position in rear of their right flank. Belatedly, three divisions were shifted to block the British flanking force at Birmingham Friends Meetinghouse and School, a Quaker meeting house.