Green attended the Boston University and received a Bachelor of Law degree in 1915. After the war, Green attended the George Washington University and received a Master of Laws degree in 1923.
He practiced law in Boston for some time. His military career began back in February 1913, when he enlisted in the Massachusetts National Guard as a Private in troop A, 1st Massachusetts Cavalry. Green served with his national guard unit on Mexican Border in 1916 and was also commissioned a Second lieutenant of cavalry in the Regular Army, in 1917.
During World War I, Green was promoted to the temporary rank of Major and ordered to the France with 2nd Cavalry within American Expeditionary Force in March 1918.
He participated in the Meuse-Argonne Offensive as a battalion commander. Subsequently he served as Assistant Judge Advocate of the 2nd Corps at Governors Island, New York City.
In 1939, Green was appointed a Chief of Patent Section in Military Affairs Section, Washington District of Columbia He was assigned to Fort Shafter, Hawaii, in August 1940 as Judge Advocate of the Hawaiian Department. Green was a Lieutenant Colonel at the time of the 1941 Attack on Pearl Harbor.
He was than appointed an Executive officer to the Military Governor of Hawaiian Islands, Lieutenant general Delos C. Emmons, and stayed in this capacity until 1943.
Green was promoted to the rank of Brigadier general on May 24, 1942. Following his service in Hawaii, he was transferred to the Washington, District of Columbia, where he was appointed a Judge Advocate General, deputy of Judge Advocate General, major general Myron C. Cramer. In this capacity, he was responsible for Military Justice and later also for Civil Justice.
He served in this capacity until December 1945, when major general Cramer was retired and Green replaced him.
Green was also promoted to the rank of Major General on December 1, 1945. Green served as Judge Advocate General until November 30, 1949, when he finally retired from the Army.
He was replaced by major general Ernest M. Brannon. After retirement from the Army, Green worked as Professor of Law and Professor Emeritus at the University of Arizona until his death.
Major general Thomas Henry Green died on March 27, 1971, at the age of 81 years.