Soon after Thomas Jefferson became president in 1801 he appointed Meriwether Lewis as his personal secretary. At this time Jefferson read about the adventures of Alexander Mackenzie. In his book, Voyages from Montreal, Mackenzie had described his two expeditions where he had tried to find a navigable route to the Pacific Ocean. For the next few months Jefferson and Lewis discussed the possibility of exploring these unknown lands.
As part of his preparation, Lewis was sent to the University of Pennsylvania to study botany, natural history, medicine, mineralogy and celestial navigation. One of his tutors was Benjamin Rush, who asked Lewis to find out from the Native Americans about their burial customs, diet, medicines, breast feeding, bathing, crime and religious practices.
On 18th January, 1803, President Jefferson requested permission from Congress to explore the vast lands to the west of the Mississippi. Jefferson claimed that there were "great supplies of fur and peltry" to be obtained from the Native Americans living in this area. He argued that the expedition would provide opportunities for "extending the external commerce of the United States".
The following month Congress approved the venture that became known as the Corps of Discovery. Meriwether Lewis selected William Clark as his co-commander of the expedition. While the two men prepared for their journey, Jefferson's emissaries in Paris were involved in negotiating in Paris for the sale of the French possessions in America. In April 1803 the two parties agreed on the terms of the Louisiana Purchase. For the cost of $15 million, the American government purchased 800,000 square miles between the Mississippi and the Rocky Mountains.
Lewis and Clark assembled a party of 30 men. The group included animal hunters, boatmen, carpenters, soldiers and blacksmiths. They took with them a Native American to serve as an interpreter. The main source of transport was a 60-foot keelboat (barge). Lewis and Clark also spent $669 for presents for those people they met on their journey. This included colored beads, calico shirts, handkerchiefs, mirrors, bells, needles, thimbles, ribbons, kettles and brass curtain rings. They also took dozens of peace medals for the Native Americans. On one side was a picture of Jefferson and on the other side was two hands clasped in friendship.
The expedition began when their keelboat left St. Louis on 14th May 1803. Their main problem during the early weeks was the attacks from gnats and mosquitoes. In his journal Lewis complained that they "infest us in such a manner that we can scarcely exist... they are so numerous that we frequently get them in our throats as we breath".
It was eleven weeks before the party encountered its first Native Americans. The Otos responded well to being given gifts but did not understand the speech made by Lewis that included the following: "The great chief of the seventeen great nations of America, impelled by his parental regard for his newly adopted children on the troubled waters, has sent us out to clear the road. He has commanded his war chiefs to undertake this long journey. You are to live in peace with all the white men, for they are his children; neither wage war against the red men, your neighbours, for they are equally his children and is bound to protect them. "
On 16th August, a member of the party, Moses Read, deserted. He was captured and was punished by being forced "to run the gauntlet four times through the party". A few days later Sergeant Charles Floyd died after suffering from a severe stomach ache.
At the mouth of the Teton River in South Dakota the party made contact with the Sioux. They were unimpressed with the gifts they received and made attempts to stop the party progressing by raising their bows. Lewis responded by ordering the cannons to be aimed at the Sioux warriors. At this the Sioux withdrew and the expedition was allowed to continue.
When the party reached the mouth of the Knife River they decided to make winter camp among the friendly Mandans. The men erected a wooden fort. It was well built and the men were able to survive temperatures of 45 degrees below zero. During the next five months Lewis had to amputate the frostbitten toes of several men in his party. Clark and Lewis also spent time interviewing Mandans about the local terrain. With this information they were able to produce maps that they felt would help them find their way to the Pacific Ocean.
Before they left on their next stage of their journey Clark and Lewis recruited two people living in a neighbouring Minnetaree village. Toussaint Charbonneau, was a French-Canadian, who could speak English and various Native American languages. The other one was Sacajawea, a Shoshoni who had been captured by the Minnetarees when she was about 11 years old and later sold Charbonneau as a slave. Sacajawea, although only 16 years of age was pregnant with Charbonneau's child.
On 7th April, 1805, the Corps of Discovery headed West. A few weeks later Meriwether Lewis shot a buffalo. Before he had time to reload he was attacked by a bear. Lewis later wrote: "It was an open level plain, not a bush within miles nor a tree within less than three hundred yards. He pitched at me, open mouthed, and full speed, I ran about 80 yards and found he gained on me fast, I then ran into the water the idea struck me to to get into the water to such a depth that I could stand and he would be obliged to swim... he declined to combat on such unequal grounds and retreated."
The Lewis and Clark party saw the Rocky Mountains for the first time on 26th May, 1805. They proceeded up the Missouri they eventually reached the Great Falls. Lewis recorded that the torrent was "300 yards wide and at least 80 feet high". It took the party 24 days to get around the falls. The party was now in Shoshoni territory and Sacajawea began to recognise landmarks and helped guide the party to the Columbia River. She was also able to introduce Lewis and Clark to her brother, Chief Cameahwait. Although reunited with her family, Sacajawea decided to continue with her work as a guide to the Corps of Discovery.
Over the next weeks the party encountered several different tribes including the Nez Perce, Chinooks and Clatsops. On 7th December, 1805, the expedition reached the Pacific Ocean. The men built a fort and remained there until heading east on 23rd March, 1806. The return journey was marred by an attempt by a group of Blackfeet to steal rifles. In the fighting that took place one warrior was killed and another was seriously wounded.
On 23rd September, 1806, the party arrived back at St. Louis. The 28 month expedition produced a considerable body of data concerning the topographical features of the county and its natural resources. They also provided details of animals and birds that lived in the territory they explored.