At one o’clock in the morning on Monday, July 17, 1865, a soldier awakened Dr. Samuel Mudd in his cell at Washington’s Arsenal prison and ordered him to get up.

Most people’s nightmares are over when they wake up, but Dr. Mudd’s was just beginning. He and three other Arsenal prisoners, Edman Spangler, Samuel Arnold, and Michael O’Laughlen, were rousted from their cells and taken in irons to a nearby wharf on the Potomac River. At the wharf, they were put aboard the side-wheel Army steamer State of Maine. The four prisoners assumed they were being put aboard the State of Maine for transport to New York, and from there to the Federal penitentiary in Albany, where they had been told they would serve their sentences. They were wrong.

About two o’clock in the morning, the State of Maine splashed away from the wharf and picked up speed as it slipped through the night down the Potomac River. By sunup, the ship was in the Chesapeake Bay, and by late afternoon it arrived at Fortress Monroe, located at Hampton, Virginia where the Chesapeake Bay empties into the Atlantic Ocean. 

One of the ships lying at anchor off Fortress Monroe that afternoon was the Navy side-wheel steamer U.S.S. Florida. At 6:30 P.M., the Florida’s commander, Captain William Budd, noted in his log book that he had taken aboard as passengers Brigadier General Dodd, Colonel Turner, Captain Dutton, and Doctor Porter, all of the U.S. Army. Also taken aboard were “4 Rebel Prisoners, with a guard of 28 men & their rations.” He would soon learn that his “4 Rebel Prisoners” were the four men who had been convicted but not hung in the Lincoln conspiracy trial.

At 7 P.M., the Florida raised anchor and set out to sea. She quickly left the Chesapeake Bay, entered the Atlantic Ocean, and turned south. One week and a thousand miles ahead lay the Dry Tortugas.

After a seven day journey, the U.S.S. Florida arrived at Fort Jefferson at 11:30 A.M. on July 24, 1865. Rain squalls kept the temperature down to 85 degrees, not too bad for the Florida Keys at the end of July. A pilot came out from the fort to guide the Florida to an anchorage. At 2 P.M., an officer from the fort came aboard to escort General Dodd and other officers ashore. An hour later, Dr. Mudd and his companions were taken ashore. O’Laughlen would not leave Fort Jefferson alive, dying two years later during the great 1867 yellow fever epidemic. Dr. Mudd, Arnold, and Spangler would not leave the island prison until March 1869 after receiving pardons from President Johnson.

When Dr. Mudd and his companions arrived at Fort Jefferson, the casemates, or gunrooms, on the second tier of the Sally Port wall were used to house prisoners. Construction of these second tier casemates had been suspended because the weight of the fort was causing it to sink into the ground. Except for their three months in the dungeon, Dr. Mudd, Spangler, Arnold, and O’Laughlen lived together in the cell  immediately above the Sally Port.
 
The four new prisoners were assigned to work according to their skills. Dr. Mudd was assigned to work in the prison hospital. Samuel Arnold, who had attended Georgetown College, was assigned to clerical work in the Provost Marshal's office. Edman Spangler and Michael O'Laughlen were assigned to work as carpenters in the fort's engineering department. Arnold said “Spangler’s trade was a godsend at this time and proved so on more than one occasion afterwards.”