The 1837 Great Plains smallpox epidemic spanned 1836 through 1840, but reached its height after the spring of 1837 when an American Fur Company steamboat, the S.S. St. Peter, carried infected people and supplies into the Missouri Valley. More than 17,000 Indigenous people died along the Missouri River alone, with some bands becoming nearly extinct. Having witnessed the effects of the epidemic on the Mandan tribe, fur trader Francis Chardon wrote, "the small-pox had never been known in the civilized world, as it had been among the poor Mandans and other Indians. Only twenty-seven Mandans were left to tell the tale." The Commissioner of Indian Affairs in 1839 reported on the casualties: "No attempt has been made to count the victims, nor is it possible to reckon them in any of these tribes w