Excerpts from Books and Wikipedia
"The controversy surrounding his marriage to Rachel remained a sore point for Jackson, who deeply resented attacks on his wife's honor. By May 1806, Charles Dickinson, who, like Jackson, raced horses, had published an attack on Jackson in the local newspaper, and it resulted in a written challenge from Jackson to a duel. Since Dickinson was considered an expert shot, Jackson determined it would be best to let Dickinson turn and fire first, hoping that his aim might be spoiled in his quickness; Jackson would wait and take careful aim at Dickinson. Dickinson did fire first, hitting Jackson in the chest. The bullet that struck Jackson was so close to his heart that it could not be removed. Under the rules of dueling, Dickinson had to remain still as Jackson took aim and shot and killed him. Jackson's behavior in the duel outraged men in Tennessee, who called it a brutal, cold-blooded killing and saddled Jackson with a reputation as a violent, vengeful man." He became a social outcast in western Tennessee. "For many years Jackson suffered intense physical pain on account of his gunfight with Charles Dickinson." [Andrew Jackson 1, p. 143]