Between 1782 and 1786, Gunn unsuccessfully challenged retired
Gen. Nathanael Greene to a duel, assailed Georgia Revolutionary War hero
James Jackson in the press, and defeated
Gen. Anthony Wayne for one of Georgia's
First U.S. Senate seats in January 1789. Gunn was selected as a delegate to the Continental Congress in 1787 but never attended sessions. In his first term as senator, between mid-May and late June 1789, Gunn moved from opposing the establishment of
excise taxes to supporting them. He also opposed giving the president the power to remove heads of cabinet departments without the advice and consent of the Senate. The administration negotiated the
Treaty of New York (1790) with the
Creek Indians, which greatly angered many in Georgia. Gunn voted against the treaty. Like no other senator, Gunn impacted the internal processes in the Senate and the relationship between the executive and legislative branches of the newly formed government during his first term in office. In August 1789, Gunn set precedence, when he effectively became the first Senator to invoke
Senatorial courtesy, when he convinced the other senators to go along with his objection of President
George Washington's nomination of
Benjamin Fishbourn to a federal position in the Port of
Savannah, Georgia. Gunn supported the formation of the Georgia Company and the sale of the
Yazoo lands. In the aftermath of the Yazoo sale, Gunn acted quickly to complete the transaction and protect it in Washington, while Jackson tried to block the completion of the sale. On June 24, 1795, Gunn voted in favor of the
Jay Treaty, one of only two southern senators to do so. James Jackson voted against it. Jackson resigned from the Senate and returned to Georgia to work against Gunn, who fell in public opinion due to the
Yazoo land fraud. Gunn was re-elected in 1795 and served out his second term until March 1801. ==Death and legacy==