George St . Leger Grenfell George St . Leger Grenfell ( May 30 , 1808 – March 1868 ? ) was a British soldier of fortune , of the Cornish family , who claimed to have fought in Algeria , in Morocco against the Barbary pirates , under Garibaldi in South America , in the Crimean War , and in the Sepoy Mutiny . Immigrating to the United States , he fought for the Confederacy during the American Civil War , and was a leader of a notorious plot to seize control of parts of the Northern U . S . Biography . Grenfell was born in London , England . He came to America in 1862 and became an officer in the Confederate States Army , serving with cavalryman John Hunt Morgan , General Braxton Bragg , and General J . E . B . Stuart . He resigned from the Confederate Army in 1864 to join a plot to take over the governments of Ohio , Indiana , and Illinois and establish a Northwestern Confederacy . When the plan to take over Chicago was discovered , Grenfell and some 150 others were arrested . In what became known as the " Chicago Conspiracy " , Grenfell was tried , convicted , and sentenced to hang . Through the efforts of the British Minister in Washington , his sentence was commuted to life imprisonment at the isolated Fort Jefferson military prison located about 70 miles west of Key West , Florida , in the Dry Tortugas islands of the Gulf of Mexico . He arrived at Fort Jefferson on October 8 , 1865 . The great majority of the 527 prisoners at Fort Jefferson when Grenfell arrived were Union Army privates whose most common transgression was desertion . A number of civilians were also being held , most for robbery . Grenfell was in a special category called " state prisoner . " There were only four other state prisoners at Fort Jefferson : Dr . Samuel A . Mudd , Edmund Spangler , Samuel Arnold , and Michael O ' Laughlen , all of whom had arrived at Fort Jefferson just two and a half months earlier after being convicted at the Lincoln assassination conspiracy trial . Unfortunately for Grenfell , Dr . Mudd had attempted to escape a few days before Grenfell arrived . Fearing a larger escape attempt of the state prisoners , the five men were confined together for the next three months in a ground level cell known as the " dungeon . " In a letter Dr . Mudd wrote at the time to his brother - in - law Jere Dyer , he said : We are all at this moment in chains . Neither Colonel Grenfel nor myself has been taken out to work the past two or three days , but suffered to remain passively in our quarters . He is quite an intelligent man , tall , straight , and about sixty - one or two years of age . He speaks fluently several languages , and often adds mirth by his witty sarcasm and jest . He has been badly wounded and is now suffering with dropsy , and is allowed no medical treatment whatever , but loaded down with chains , and fed upon the most loathsome food , which treatment in a short time must bring him to an untimely grave . You will confer an act of kindness and mercy by acquainting the English Minister at Washington , Sir F . A . Bruce , of these facts . In an April 16 , 1867 , letter to Tom Dyer , his wife ’ s brother in New Orleans , Dr . Mudd again wrote of Grenfell : Colonel St . Ledger Grenfel is kept in close confinement under guard . A few days ago , being sick , he applied to the doctor of the Post for medical attention , which he was refused , and he was ordered to work . Feeling himself unable to move about , he refused . He was then ordered to carry a ball until further orders , which he likewise refused . He was then tied up for half a day , and still refusing , he was taken to one of the wharves , thrown overboard with a rope attached , and ducked ; being able to keep himself above water , a fifty pound weight was attached to his feet . Grenfel is an old man , about sixty . He has never refused to do work which he was able to perform , but they demanded more than he felt able , and he wisely refused . They could not conquer him , and he is doing now that which he never objected doing . In a 1926 " Saturday Evening Post " article , author George Allan England provided a description of Colonel Grenfell , as told to him by a former Fort Jefferson lighthouse keeper : All sorts and conditions were herded into the prison of Dry Tortugas . The greatest mystery man of them all was a fiery swashbuckler known as Col . St . Leger Grenfell . ' He was a queer bird altogether , ' one William Felton told me at Key West . Felton was long a custodian at the fort , and can rock on his front porch and spin yarns about it by the hour . ' Grenfell was sure one tough lookin ’ customer , six foot tall , black - haired , an ’ with black eyes under big , bushy eyebrows . He had a tremendous black beard , too , an ’ wore a red flannel shirt open at the neck , an ’ his pant legs tucked in high boots . Folks said he was a son of Sir Roger Grenfell , an earl , or somethin ’ swell like that . ' Colonel Grenfell was afflicted with yellow fever during the height of an epidemic in September 1867 . In letters to his wife , Dr . Mudd wrote " Colonel Grenfel is quite sick with the disease ; he was taken yesterday . I will do all that is possible to save him . " And , " Colonel Grenfel is quite sick ; his case is doubtful . " But in the end , Dr . Mudd was able to save his life and Colonel Grenfell recovered . Dr . Mudd ' s final mention of Colonel Grenfell is in an April 14 , 1868 , letter to his wife . In it he says " We have heard nothing from Grenfel since he escaped on the 6th of last month . All hands may have perished , it being quite stormy at the time . " Colonel Grenfell , a highly experienced sailor , and three others had escaped from Fort Jefferson in a small boat . The military report of the escape said : . . . Private William Noreil of Company I 5th US Arty who had been on duty posted as a sentinel over the boats within the boom , did between the hours of 11 o ’ clock P . M . and 1 A . M . desert his post , taking possession of a small boat and carrying with him the following named prisoners – G . St . Leger Grenfell , J . W . Adare , James Orr and Joseph Holroya . I am impressed with the belief that Grenfell had considerable money in his possession by and through which he bribed the sentinel . The surveying steamer Bibb which was lying in the harbor was dispatched in pursuit of them about 8 o ’ clock the same morning but after cruising the whole day failed either to overhaul or hear anything concerning them . Most assumed that Grenfell and the others perished at sea , but there were persistent rumors he had survived . On June 5 , 1868 , the following announcement , originally published in the Mobile , Alabama , " Advertiser " , appeared in the " New York Times " . St . Leger Grenfell – The public was greatly gratified not long since to learn that this gallant English soldier had escaped his prison at the Dry Tortugas , and in his love of liberty at the risk of life , he had trusted himself to the mercies of a frail boat in an attempt to cross the Florida Straits to Cuba . We have the pleasure of stating that his voyage was made in safety , and that a letter has been received from him in Havana , sending his thanks and acknowledgements for kind treatment to some of the army officers at Tortugas , and stating that he was just about to sail for Old England . We do not doubt that every gentleman officer belonging to the garrison of his prison guard rejoices at his escape . Most historians believe that notices such as this about Grenfell were fabrications . All that is known for sure is that Grenfell was never heard from again .