Born in Providence, Rhode Island, he received his early education under private tutors, and graduated from Brown University in 1841 and, in 1845, the law department of Harvard University, gaining admission to the bar that year.
He was a lawyer and historian, and was trustee of Brown University from 1848 to 1880. This is an original idea to be sure.."
Arnold was elected lieutenant governor of Rhode Island in 1852 and served as Acting Governor. in 1861 in an effort to devise means to prevent the impending war. In March 1861 Arnold was again elected Lieutenant-Governor after being nominated by the Constitutional Union and Democratic Conventions.
Arnold was again elected Lieutenant-Governor in 1862.
During the Civil War he raised a company of light artillery which went to Washington District of Columbia and was mustered into the Union Army. He was elected as a Republican to the United States. Senate to fill the vacancy caused by the resignation of James F. Simmons, and served from December 1, 1862, to March 3, 1863.
After his time in the Senate he returned to historical research and was president of the Rhode Island Historical Society from 1868 to 1880. Arnold died in Providence in 1880.
Interment was in Swan Point Cemetery.
Theodore Francis Green, Samuel Arnold"s grandnephew, was also a United States. Senator from Rhode Island. Samuel Greene Arnold was the author of the 2-volume History of the State of Rhode Island and Providence Plantations published in 1859-1860.
American Academy of Arts and Sciences]
He was a member of the peace commission held at Washington, District of Columbia