Louisiana became a U.S. state just one and a half months before the U.S. Congress declared war upon Great Britain. During the War of 1812, Edward Livingston was active in rousing the ethnically-mixed population of New Orleans to resistance against the threat of British invasion. He used his influence to secure amnesty for Jean Lafitte and his followers when they offered to help defend the city, and in 1814–15 acted as adviser and one of several aides-de-camp to Major General Andrew Jackson, who was his personal friend.