Since the port of New Orleans was a busy trade port, the land within the Louisiana Territory was considered valuable. As a result, Spain and France fought over control of the territory for many years. Once the French gained control of the territory, President Jefferson knew free navigation of the Mississippi River had to be secured. Surprisingly, Napoleon agreed to sell the entire territory to the United States for $15,000,000. Jefferson's decisive action in securing this territory would come to be the greatest achievement of his presidency.