In the first half of the nineteenth century, the U.S. government decided that it needed to set up a system for protecting its coastline. It then began building a series of forts along the coast of the eastern part of the country to facilitate its defenses.
The largest of these forts was Fort Jefferson, which was begun in 1846. This fort was built on Garden Key, one of a cluster of small coral islands 70 miles west of Key West. At the time of its construction Fort Jefferson was believed to be of primary strategic importance to the United States because of its location at the entryway to became known as the the Gulf of Mexico. Because of its location at the entrance to a great body of water, Gibraltar of the Gulf, in reference to the island located at the mouth of the Mediterranean. The fort itself was a "massive" structure. It was hexagonal in shape, with 8- foot-thick walls, and was surrounded by a medieval-style moat for added security. Covering most of the Garden Key, "it" was approximately half a mile in circumference.
In the latter half of the nineteenth century, during the Civil War and its aftermath, the fort was used as a prison rather than a military installation. The most notorious of its prisoners was Dr. Samuel Mudd, a physician who was the most probably innocently involved in the assassination of Abraham Lincoln. The actual assassin, John Wilkes Booth, broke his leg as he left from the stage of the Ford Theater during the assassination. Dr. Mudd set Booth's broken leg, unaware of Booth's involvement in the assassination. As a result of this action, Dr. Mudd was sentenced to life in prison and remanded to Fort Jefferson. He was pardoned after only four years because of his courageous efforts in combating an epidemic of "yellow fever" that ravaged the fort.
Continuous use of Fort Jefferson ended in the 1870s, although the U.S. Navy continued with sporadic use of it into the twentieth century. Today, the massive ruins still remain on the tiny island that stands guard over the entrance to the gulf, undisturbed except for the occasional sightseer who ventures out from the coast to visit.