Samuel G. Clark was born around 1841 in North Canaan, Connecticut, to William and Mary Clark. His father was a carriage maker and farmer laborer. He grew up and attended school in Ridgefield, Connecticut, and by 1860, he was working as a lime burner.
He enlisted in the Union army on August 6, 1862, and he mustered in as a private in Company C of the 17th Connecticut Infantry on August 28. The regiment took part in the Battle of Chancellorsville and the Battle of Gettysburg. He was discharged for disability on November 9, 1863.
He settled in Danbury, Connecticut, after leaving the army. He applied for a federal pension in April 1864 and eventually received one. He married Hannah Webb around 1862, and they had at least eight children: Samuel, born around 1863; William, born around 1865; Edith, born around 1867; Nellie, born around 1869; Elmer, born around 1872; Gertrude, born around 1875; Clifford, born around 1877; and Frank, born around 1880. He earned a living as a hatter.
They moved to Bethel, Connecticut, in the late 1800s, and his wife died in 1908. By 1910, he was living with two grandchildren in Bethel. He died of pneumonia in Danbury, Connecticut, on June 16, 1910.