An accomplished carpenter and boat builder, Patrick Gass proved to be an invaluable and well-liked member of the Lewis and Clark expedition. Promoted to sergeant after the death of Charles Floyd, Gass was almost certainly responsible for supervising the building of Forts Mandan and Clatsop. His records of those forts and of the earth lodges of the Mandans and Hidatsas are particularly detailed and useful. Gass was the last survivor of the Corps of Discovery, living until 1870 - long enough to see trains cross a continent that he had helped open. His engaging and detailed journal became the first published account of the Lewis and Clark expedition.