[1][2] He served in the United States Navy during the Korean War, including service on the aircraft carrier USS Philippine Seat (CV-47), and reached the rank of lieutenant.

Instead, he ran for the Senate but narrowly lost a runoff berth in the Democratic primary to his colleague from the Second District, Jim Guy Tucker, and his colleague from the Fourth District who had also served two terms as Arkansas Governor, David Pryor, with Governor Pryor prevailing in the primary and without Republican opposition in November.

In January 1997, after another three terms with only nominal opposition, Thornton left Congress, seeking a seat as an associate justice of the Arkansas Supreme Court, for which he was unopposed.

[3] After retiring from the court, he became the first public service fellow for the William H. Bowen School of Law at the University of Arkansas at Little Rock.

[3] Ready for retirement, Thornton resigned that post after serving a year, during which the Commission supervised the establishment of the Arkansas Scholarship Lottery.