James Robert Thornley lived nearly his entire life in Fall River, Massachusetts. He made his living as a carpenter and a contractor. He served his country in the 2nd Connecticut National Guard Infantry Regiment beginning in 1916, at which time his unit was federalized and became C Company, 102nd Infantry Regiment of the US Army. He was deployed to the Mexico border in Texas to help chase Pancho Villa under the command of General Pershing. Later, when the United States entered World War I, he was deployed with this unit to France and took part in several battles, including Seicheprey and the St. Mihiel Salient. It was during the battle of Seicheprey that he earned the Army Distinguished Service Cross and the French Croix de Guerre for his actions. His citation reads:

"The President of the United States of America, authorized by Act of Congress, July 9, 1918, takes pleasure in presenting the Distinguished Service Cross to Corporal James R. Thornley (ASN: 64014), United States Army, for extraordinary heroism in action while serving with Company C, 102d Infantry Regiment, 26th Division, A.E.F., at Seicheprey, France, 20 April 1918. Wounded early on the morning of 20 April 1918, Corporal Thornley displayed great gallantry and devotion to duty in continuing to urge his men to defend their positions, aiding greatly in the defense of same by climbing in a tree and from there shouting out directions as to the enemy's location. General Orders: War Department, General Orders No. 99 (1918), Action Date: 20-Apr-18, Service: Army, Rank: Corporal, Company: Company C, Regiment: 102d Infantry Regiment, Division: 26th Division, American Expeditionary Forces"

After the war he returned to marry Caroline Belle Bowman Sedgwick of Falls Village, Connecticut and they settled in Fall River, Mass.