 With talk of secession increasing in Texas, Wilcox, a strong supporter of states rights, was selected as a delegate to the state's Secession Convention in 1861.He served on the committee that drafted the ordinance of secession.He was elected to the First Confederate Congress in November 1861 and traveled to Richmond, Virginia to assume his duties, serving on various committees and proving to be a staunch support of the policies of President Jefferson Davis.