James M. Mathewson was a resident of Mansfield on June 21, 1861 when he enlisted as a Private in Co. B of the 5^th Regiment Connecticut Volunteer Infantry; he was promoted to Corporal September 1, 1864 and mustered out July 19, 1865 at Alexandria, Virginia.

He was born April 13, 1837 in Connecticut to Edwin and Sarah (_____) Mathewson. In the 1850 U.S. census in Worcester, Massachusetts, he is a 13 year old in the household of Edward/Edwin Mathewson. His family was in Ashford by the time of the 1860 U.S. census, but James is not enumerated with them. James Mathewson married Frances J. Joslin about 1870. Children include: George T. Mathewson, born about 1874 and Chester S. Mathewson, born about 1876. After the Civil War, he moved to the Joslin homestead in Thompson and worked as a carpenter.

On September 29, 1879, he applied for an invalid pension, No. 312,442 that was granted under certificate No. 206103.  

James M. Mathewson died on September 24, 1910 in Thompson and is buried at the Joslin Cemetery in Thompson, Connecticut