Around the same time, he enlisted in the United States Army and participated in military action against the Cherokee Nation percipient to the Trail of Tears.

[2] Clemens joined the Democratic Party and was appointed the United States Attorney for northern and middle Alabama by President Martin Van Buren in 1839.

[3] Clemens was elected to the United States Senate in 1849 to fill the vacancy left by the death of Dixon Hall Lewis.

The Unionists swept the 1851 elections in Alabama, carrying two-thirds of the state's counties; however, Clemens was not re-elected to the Senate when his term ended in 1853.

[4][5] Following his departure from the Senate, Clemens joined the Know Nothing movement and was an unsuccessful candidate for the House of Representatives that year on the American Party ticket.

When the delegates voted in favor of secession, however, Clemens reluctantly signed the ordinance announcing Alabama's departure from the Union.

His final novel, Tobias Wilson, published posthumously in 1865, was an account of Unionist partisans who fought during the Civil War in the mountains of Alabama near Clemens' hometown of Huntsville.