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  • Writer's pictureGordon Thorsby

A Sentence for Desertion Worse Than Execution 1861-65, Dry Tortugas

Updated: Oct 23, 2022

by Gordon Thorsby

Blacksmith Thomas Nevins , Captain Lester D. Wilson of Co. F, 75th New York Infantry Regiment, and unidentified soldie3 (LOC)

It was called America’s Devil’s Island, the “Gibraltar of the South” and for a couple of centuries Dry Tortugas. Officially it was named Ft. Jefferson. A wife of one officer simply described the fortress as "a dark, mean place." It was a place of intense heat and disease. Fortunately, it received rain because there was no other source of water. In September 1861, it became the alternative to execution when it welcomed the first group of court-martialed deserters from the Union army.

Dry Tortugas became known as a worse sentence than the firing squad for over 1000 deserters who were imprisoned there. John Cannivan was one such deserter (a.k.a. Canavan, Cannavan, and possibly by the name Sullivan.)

(Note: Researching Cannivan was difficult and his story has many gaps. His aliases are responsible.)

Cannivan was born in 1832 to some of the earliest Irish immigrants to Canada. There is no verifiable information what he did the first 32 years, but we do know what he did for the next four years. He may have gone to sea. and this may be how he came to New York City in May 1861.

The Civil War had broken out in April when a John Cannavan at the Port of New York was wanted for desertion from a Navy vessel. On May 13, 1861, Canadian John Cannivan enlisted in Co. F, 36th New York Volunteer Infantry as a Private at Camp Reed, Riker’s Island, New York Harbor. The recruits were immigrant Britons and Irish and provosts had to constantly break up fights. It is likely that Cannivan was a bit of a “tough” and he would need it. The regiment officially mustered June 19, a bounty was paid to the recruits and on July 11, John disappeared. He was listed as deserted and the next day, the regiment departed for Washington.

John Cannivan was indeed gone but on 30 September, he enlisted in Company A, 75th New York as Private. He reported his residence as Moravia, NY (Finger Lakes region). John and the first five companies were designated to be sharpshooters. The regiment began the official muster process between October and November and once again, John deserted. However, this time, the Provost Marshals were more efficient and caught him. As officials pondered his fate, the multiple offenses caught up with him and the case of John Cannivan was escalated to a full court-martial with a probable sentence of execution.

Cannivan might have considered it good luck when President Lincoln introduced a new policy in 1861. Lincoln preferred badly needed volunteers and execution sentences became open ended prison sentences at Dry Tortugas. Cannivan’s thoughts of “getting off” would be premature as would several hundred fellow deserters that joined him.

Fort Jefferson (70 miles west of Key West) was the largest masonry fort in the U.S. at the time and Federal Authorities were still trying to complete construction. Black slaves had been utilized for the past 15 years but deserters became a more acceptable source of hard labor. The 50-foot high walled prison was opened in September 1861, and Cannivan arrived in November.

The fort was built on a spit of sand three feet above high tide when the Gulf was becalmed. There was nothing else. Fresh water, food, supplies, and people all came by ship. Living conditions were unbearable. The inescapable heat from the sun was punishing. Humidity resulted in mildew and continuous rot. Swarms of flies, mosquitoes and gnats were unrelenting. Fresh water from rain was plentiful and was collected in cisterns and the fort was an excellent stopping point for blockading ships.

The population of unexecuted deserters quickly swelled as did the troops to guard them. In 1864, as Cannivan had passed two years of incarceration, there were 1729 guards and 883 deserters. Cannivan and his cohorts labored sunrise to sunset six days a week, ach each man in irons.

As time wore on, disease from poor sanitation worsened. Dysentery, yellow fever and malaria flared. There were eight documented escapes, but none are known to have survived. By January 1865, the fort’s population declined to 1,013, including 527 prisoners. In November,1864, John Cannivan marked his third year at Dry Tortugas and was surprisingly still alive.

There is no record as to how exactly Cannivan survived. On 7 January,1865 John Cannivan received orders to return to the 75th New York. He shipped up to Savannah where he met the regiment that had just arrived to garrison the city. During Cannivan’s captivity, the 75th experienced some of the worst service including Port Hudson, Red River Campaign, Petersburg, and the Shenandoah Campaign. The soldiers in the ranks would not have welcomed him and he probably experienced a new “hell” from men who resented his crimes. He mustered out in August 1865.

John Cannivan resettled in the quiet, small town of New Lothrop, MI. It was a remote place where nobody from the area was in the 36th NY, the 75th NY or known of Dry Tortugas, a hell for deserters. He married but kept to himself and he did not join the Ransom GAR. His widow filed for a widow’s pension. It was probably denied.

John Cannivan died August 2,1899 and is buried in Maple Grove Cemetery. There are lots of trees that block the rays of a harsh sun on John’s grave.

From Wikicommons


Historical Data Systems, Inc., P.O. Box 25, Sudbury, MA 03331.

American Battlefield Trust, Battlefields and Heritage Sites Fort Jefferson, Dry Tortugas National Park

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