Sir Ranulph Fiennes looks at the life and death of Merriweather Lewis, the explorer who led a three year expedition across America, uncovering and mapping a route to the Pacific, uniting both coasts and starting the Westward expansion.
In 1804 Merriweather Lewis made the equivalent of a moonwalk when he stepped off the edge of the known world with his 33 man strong Corps of Discovery.
A new type of explorer, he had been charged with finding a route to the Pacific and to explore the West - a land some Americans believed to be the home of Prehistoric animals and volcanoes.
Lewis and his co-commander for the journey, William Clark walked, rode and canoed their way across the continent, a rip-roaring adventure through the 'great nothing', the vast blank uncharted region on the map of America.
They travelled 8,000 miles and discovered over 180 new species of animals and over 200 new species of plants.
They met with the tribes living on the Great Plains, were attacked by Grizzly bears, survived starvation, and were given up for dead by their country.
When they finally returned they were hailed as heroes, yet by 1807 Lewis was a bankrupt, political liability, a depressed, alcoholic suicide who bled to death alone at a lonely road stop on a lost American highway (the Natchez-trace trail).
Lewis' achievements with the Corps of Discovery were remarkable, even more so when you realise that the 30 year old former presidential secretary suffered from bi-polar depression.
In three years he lost just one member of his team, and then to a disease which was inoperable at that time.