After the American defeat at Brandywine on September 11, 1777, British forces pushed toward Philadelphia, then the seat of the Continental Congress. By September 26, the British entered and occupied the city, forcing Congress and other Patriot officials to flee west rather than risk capture. The flight turned Lancaster into a temporary refuge for the revolutionary government at one of the war’s most precarious moments.

Lancaster was not merely a hiding place; it was also a practical supply center. A few days earlier, on September 23, 1777, George Washington wrote to John Hancock urgently asking that any available “Shoes & Blankets” in Lancaster or the surrounding countryside be gathered for the army, noting that he had heard there were especially large quantities of shoes there. That request captures Lancaster’s wartime importance: a place of craftsmen, merchants, farms, roads, and stores of goods that could support the Continental cause.

On September 27, 1777, Congress convened in Lancaster’s courthouse, located in the square at the center of town—today’s Penn Square. That single session made Lancaster, for one day, the capital of the United States. But the delegates did not consider Lancaster secure enough for a longer stay. At the end of the day, they resolved to adjourn across the Susquehanna River to York, where they would meet the following Tuesday, placing the river between themselves and the British army and giving the revolutionary government greater protection.