Thomas F. Harney

Thomas F. Harney was a Confederate explosives expert, who was arrested by the Union Army in the final days of the US Civil War, seemingly en route to bomb the White House.

Plot
On March 22, 1865, John Wilkes Booth, Sarah Slater, and colleagues met at the St. Nicholas Hotel in New York City where they learned that the White House had an underground entrance beneath the cabinet offices. They had no explosives or expertise to use that information.

On March 25, Slater was at the Surratt boardinghouse and tavern although her escort, Augustus Howell, had just been arrested. John Surratt accompanied her to meet Judah Benjamin on March 29 in Richmond, Virginia, where he registered a room as "Harry Sherman". Benjamin withdrew US$1500 in gold, giving US$200 to Surratt as payment for getting the remaining Montreal money, US$650000, couriered safely to France or England.

General Gabriel Rains of the Confederate Naval Ordnance Bureau received a message the same day to send a demolitions expert to Virginia to meet with Mosby for insertion into DC. Harney was dispatched towards Richmond, based on his work as a "torpedo planter" working on the CSS Hunley, but on April 2, 1865, the city was evacuated. Mosby, Slater and Surratt were among those scattering—Harney took a train to Gordonsville where he is believed to have met Major Cornelius Boyle to pass a further message to Mosby. Boyle then gave Harney a horse and a guide believed to be Thomas Franklin Summers, who would help him reach Washington, DC. During those same days, Mosby sent his friend Capt. Robert S. Walker to meet with Boyle "to learn the true state of affairs".