American prisoners captured before 1778 were not legally 'prisoners of war'. Not until March 25, 1782, (six months after Yorktown) did Parliament pass a law designating Americans as prisoners of war, allowing them to be detained, released or exchanged. This provided the British with a free hand to treat their captives in any manner they saw fit.
There were thousands of American prisoners held by the British during the war.
Of all of the prisoners held in captivity, 4 out of 5 men died.
New York City was the main city where prisoners were held.
By the end of 1776, there were over 5,000 prisoners held in New York City. More than half of the prisoners came from the soldiers captured at the battle of Fort Washington and Fort Lee. With a total population of New York City around 25,000, this meant that 1 out of every 5 people in the city were prisoners.
During the war, more military men on the British prison ships than were killed in battle.
A Prisoner Excange Program was used between the British and American forces during the American Revolutionary War. The premise of the exchange was to be able to exchange a sailor for a sailor, a soldier for a soldier, with the prisoners being of equal rank. Later on in the war, the exchange program was stopped by the British in 1780. The reason being that with the American forces being smaller than the British forces, the British didn't want to let the Americans get back more of their men by using the rate of attrition being that the Americans didn't have nearly as many military personel as the British.After the major british defeat at the battle of Yorktown in 1781, the British wanted to restart the program due to the severe shortage of soldiers and sailors in the British military. Gen. George Washington realized this, and with the war coming to an end with the Americans seeing that they were going to be victorious, decided to not start the program back.
Prisoners onboard the British prison ships could win their release if they signed an oath to serve as sailors with the British Royal Navy.
In the latter years of the war, the number of enlistments of British sailors were becoming smaller and more difficult to fulfill. To offset the low recruiting numbers, the British government authorized a plan whereas the American prisoners would be allowed to sign an oath to serve in the Royal Navy in exchange for being released from captivity as prisoners of war.
By the end of the war, almost 25% of the sailors serving aboard ships in the British Royal Navy were former American prisoners who signed the oath.