 Upon the resignation of Representative-elect John B. Lamar, Chappell was elected as his replacement in the U.S. House of Representatives in 1843 and served in that position until 1845 when he did not seek re-election.Chappell was subsequently elected to one more term as a state senator in 1845 and served as the president of that body.In 1842 he married Loretto Rebecca Lamar, the younger sister of Judge Lucius Quintus Cincinnatus Lamar (I) and Mirabeau B. Lamar, second President of Texas.