primary defense system. British occupation In 1763, the British managed to take control of the Castillo but not by force. As a provision of the Treaty of Paris (1763) after the Seven Years' War, Britain gained all of Spanish Florida in exchange for returning Havana and Manila to Spain. On July 21, 1763, the Spanish governor turned the Castillo over to the British, who established St. Augustine as the capital of the province of East Florida, established by the Royal Proclamation of 1763. The British made some changes to the fort, and renamed it Fort St. Mark. As Great Britain was the dominant power in North America, they were not worried about keeping the fort in top condition. This attitude prevailed until the outbreak of the American Revolutionary War. The fort was used as a military prison during the war. Among those imprisoned was Christopher Gadsden, the Lieutenant governor of South Carolina. He was also a delegate to the Continental Congress and a brigadier general in the Continental Army during the war. He was released after 11 months. Improvements were begun on the fort, in keeping with its new role as a base of operations for the British in the South. The gates and walls were repaired, and second floors were added to several rooms to increase the housing capacity of the fort. The Castillo saw action during the American Revolution mainly as a prison, although St. Augustine was targeted by several aborted expeditions from Georgia. Several revolutionary fighters who had been captured in Charleston were held there when it was taken by the British, including three Founding Fathers; Thomas Heyward Jr., Arthur Middleton, and Edward Rutledge. The Spanish declared war on Britain in 1779, drawing off forces from Fort St. Mark and keeping the British occupied. Bernardo de Gálvez, governor of Spanish Louisiana, attacked several British-held cities in West Florida, capturing all of them. The only major British operation that used troops from St. Augustine was the poorly coordinated but successful capture of Savannah, Georgia; the city was taken by troops from New York before those from St. Augustine arrived. At the end of the war, the Peace of Paris (1783) called for the return of Florida to Spain. On July 12, 1784, Spanish troops returned to St. Augustine. Second Spanish period When Spain regained control over Florida they found a much-changed territory. Many Spaniards had left Florida after