The surrender of General John Burgoyne to General Gates at Saratoga, NY, on October 18, 1777, placed nearly 6,000 British, Hessian, and Canadian prisoners of war in the hands of the Continental Congress, then in session at York, Pennsylvania. An official report states that 5,800 troops surrendered at Saratoga, of which there were 2,400 Hessians and the remainder were British citizens. According to the terms of their surrender, written in a document entitled the "Convention of Saratoga," the prisoners were to be marched to Boston, and shipped back to Great Britain. If any of the prisoners desired to remain in America, they were permitted to escape.
When the prisoners of war arrived at Boston, they were quartered on winter and Prospect Hills. Congress, wanting to ensure that none of the officers returned to the battlefield, asked that General Burgoyne write a descriptive list of each of the officers under his command. This request was not specified in the Convention of Saratoga, and General Burgoyne became personally offended and refused to heed the request. On the 8th of January 1778, Congress resolved to suspend the terms of the Convention of Saratoga, and kept the prisoners in custody.
After remaining in the Boston area for the winter, the decision was made to relocate the prisoners to Charlottesville, Virginia, where they could be more closely watched and better supplied. In November 1778 the prisoners marched southward. Many of the British officers had their wives and children with them, and wagons were provided for their transportation but the men had to march on foot. They traveled through Lancaster and York, PA in December of the same year, and finally reached Charlottesville, 550 miles from Boston, in January 1779.
They constructed a rectangular camp there, but the war came to Virginia and Continental Congress to the north, to Fort Frederick, in western Maryland. The march northward began in October 1780 to Winchester, Virginia, and then Fort Frederick.
Congress then ordered the prisoners to be moved again, this time into the heart of well-controlled Pennsylvania. There were by this time about 3,000 of Burgoyne's officers and men held. Joseph Reed, then President of Pennsylvania, objected to the number of prisoners being brought into his state. In response to his objection, the Board of War asserted that Congress would not change its decision and that Pennsylvania must begin looking for a suitable site to house these prisoners. At the same time, Governor Thomas Lee of Maryland wrote to President Reed, to inform him that Governor Thomas Jefferson of Virginia had told him that the British that had been captured at Cowpens, South Carolina, were also on their way to Pennsylvania and the British prisoners at the town of Frederick, 800 in number, were also being relocated to York.
Although President Reed again protested about being the main location for the British prisoners in the country, Congress would not budge. The British prisoners began to reach Lancaster, PA in early June 1781, and were quartered at the Lancaster Barracks there and on the village green. On June 30, 1781, President Reed was instructed to separate the men, and move the Hessian troops to Reading and the British to a camp near York.