At the price of 15 million dollars Jefferson bought the Louisiana purchase which more than doubled the size of the u.s. President jefferson sent two explores named lewis and clark to scope out the new land that he just bought. On their expedition, they were assisted by Sacagawea, a local  Native American who helped them navigate through the land because she knew the native land far better than the European travelers. Together the explorers brought back valuable information about the west and showed the transcontinental travel was possible within  the United States

President Jefferson, Meriwether Lewis, William Clark, Patrick Pass, Sacajawea,Napoleon were the main people to help president Jefferson  purchase land in the louisiana making america difficult to attack.