The family emigrated to the United States during the 1840s and settled on a farm near West Hartford, Connecticut.
Aged 12 years, he changed his name to Benjamin Franklin Arnold and went to live with a family in Gilbertsville where he attended the local Academy.
Arnold was Supervisor of the Town of Unadilla from 1879 to 1885; Chairman of the Board of Supervisors of Otsego County in 1881; a member of the New York State Assembly (Otsego Co., 2nd D.) in 1885, 1886 and 1887; and a member of the New York State Senate (23rd D.) in 1888 and 1889.
During the election campaign, the newspapers unearthed the fact of his name change and intimated that it had been done "for dishonorable and degrading reasons."
Depressed by the defeat and the slander campaign, he shot himself dead in his office with a pistol which had been the "murder weapon" in a case which he had defended in 1887, when he had obtained a verdict of manslaughter for his client.