Thomas Jefferson showed personal exercise of power when he purchased the Louisiana Territory from France in 1803, greatly expanding U.S. territory. He addressed immediate national needs through the 1807 Embargo Acts, which stopped the seizure of American ships and sailors by foreign countries like Britain during conflicts. Jefferson also demonstrated formal presidential powers and roles as chief diplomat and commander by refusing payment demands from Pasha of Tripoli, blockading the nation with warships until negotiations were successful.