The area was an active place in the early 19th century. A former British officer named William Augustus Bowles led 400 Creek Indians in an attack to take control of San Marcos. This angered Spain. A Spanish flotilla got to the area about 5 weeks later. The Spanish took control of San Marcos. In 1818, General Andrew Jackson attacked (Wakulla) and took control of San Marcos. Two British people, Robert Ambrister and Alexander Arbuthnot, were said to have started Indian raids. They were found guilty of the crime and killed. This caused large diplomatic problems between the United States and England. In 1821, Florida was became a part of the United States. San Marcos controlled by U.S. troops. In 1824, the fort was no longer used. Control of it was given to the Territory of Florida. By 1839, the fort was returned to the U.S. A federal marine hospital was built. The hospital helped people with yellow fever in the area.