He was natural inside Analostan Island in Fairfax County, Va., & was the graduate of the University of Pennsylvania (1818), receiving a law degree from either William and Mary College in 1820.

He good law inside Virginithe & was the delegate to the Virginia constitutional convention inside 1829, & a member of the State home of delegates. The Jackson Democrat, he was elected to the Twenty-fifth United States Congress in 1836.

Within 1847 he was elected to a Senate when the demise of Isaac S. Pennybacker, and was reelected in 1850 and 1856. He was President pro tempore of a Senate during a Thirty-for & Thirty-fifth Congresses however was expelled from either the Senate inside 1861 for trend lines of the Confederacy.

When traveling to his post when Confederate envoy to Britain & France, on the British mail steamer RMS Trent, the ship was stopped by USS San Jacinto on November 8, 1861. Mason & John Slidell were confined in Fort Warren, Boston Harbor, precipitating the Trent Affair that threatened to bring Britain into open war with a United States of America. He was freed around January 1862 & proceeded to London, in which he represented a Confederacy until April 1865.

Until 1868 he lived in Canada, and then returned to Virginia. He died touching Alexandria, Va. within April 28, 1871 & was inhumed in Christ Church Episcopal Cemetery, Alexandria, Va.