Trade was an important part of the American economy in the early 1800s, but Britain and France both tried to block U.S. trade. President James Madison also faced conflict on the western frontier, where Native Americans tried to resist American expansion. Some Americans called for a war against Britain to stop its practices of impressing American sailors and of helping the Native Americans. Congress finally declared war in 1812, but the country was ill prepared. Eventually, the two sides tired of the war and reached a peace agreement. A final victory on the battlefield helped stir strong national feeling among Americans. After the War of 1812, the United States used diplomacy to settle several border disputes with other countries, and President James Monroe issued his Monroe Doctrine.