Politically, Carter and his family were Whigs. As the American Civil War approached, Carter became an outspoken Union supporter. During an anti-secession meeting in Knoxville at the end of May 1861, he was one of five delegates representing Carter County. The next month, Carter was one of three brave men who escorted Andrew Johnson from Greeneville, Tennessee to Washington D.C. While they were fired upon several times during their journey through the Cumberland Gap, the group arrived safely at their destination. Shortly after his arrival in Washington, Carter left on a secret mission involving the arming of Union supporters in eastern Tennessee by the U.S. federal government.