One of Jefferson's acts doubled the area of the country. At the end of the Seven Years' War, France had ceded to Spain the territory west of the Mississippi River, with the port of New Orleans near its mouth -- a port indispensable for the shipment of American products from the Ohio and Mississippi valleys. Shortly after Jefferson became president, Napoleon forced a weak Spanish government to cede the great tract called Louisiana back to France. The move filled Americans with apprehension and indignation. Napoleon's plans for a huge colonial empire just west of the United States threatened the trading rights and the safety of all American interior settlements. Jefferson asserted that if France took possession of Louisiana, "from that moment we must marry ourselves to the British fleet and nation."