What were the main diplomatic achievements of the period between the end of the war of 1812 and the coming civil war?

Between the end of the War of 1812 and the Civil War, key diplomatic achievements included the Rush-Bagot Agreement of 1817, which demilitarized the Great Lakes, and the Convention of 1818, establishing the U.S.-Canada border at the 49th parallel. The Adams-Onís Treaty of 1819 resulted in Spain ceding Florida to the United States and defined the western boundary of the Louisiana Purchase. Additionally, the Monroe Doctrine of 1823 asserted U.S. opposition to European colonialism in the Americas, shaping future foreign policy. These agreements helped solidify U.S. territorial claims and enhance its international standing.