George Arnold, Sr. and Mary Jane Bland Arnold

Arnold joined the Confederate Army during the Civil War but was discharged for health reasons. He returned to Baltimore, and in the late summer of 1864, was recruited by Booth to be part of the plot to kidnap President Lincoln.

Being unemployed and bored, Arnold eagerly accepted the plan. On the night of Wednesday, March 15, 1865, Arnold met with Booth and other conspirators at Gautier's Restaurant on Pennsylvania Avenue to discuss the possible abduction of the president. Two days later Arnold was involved in a plan to kidnap Lincoln on the road to the Campbell Hospital. There the president had planned to attend a performance of the play Still Waters Run Deep. Lincoln changed plans at the last minute, and this plan fell through. (It is likely John Surratt embellished the story of this kidnapping attempt in his 1870 lecture. In reality Lincoln remained in Washington to speak to the 140th Indiana Regiment from the balcony of the National Hotel.) After this failure, Arnold returned to Baltimore but ended up taking a clerk's job in Old Point Comfort, Virginia. On March 27, he wrote Booth a letter requesting that Booth desist from his plans and indicating, at least temporarily, he (Arnold) would be separating himself from Booth's gang.

Arnold was working at this job in Virginia when he was arrested on April 17, 1865. He admitted his part in the plot to kidnap Lincoln. However, his co-workers supported Arnold's contention that he was in Virginia at the time of the assassination. Still, the U.S. government charged him with conspiracy, and he went to trial along with Mary Surratt, Lewis Powell, David Herold, George Atzerodt, Ned Spangler, Dr. Samuel Mudd, and Michael O'Laughlen.

Arnold was found guilty by the Military Commission and sentenced to life. With Mudd, Spangler, and O'Laughlen, he was sent to Ft. Jefferson in the Dry Tortugas.