text: The Mandan believed that they had been infected by whites associated with the steamboat and Fort Clark. Chief Four Bears reportedly said, while ailing, "a set of Black harted  Dogs, they have deceived Me, them that I always considered as Brothers, has turned Out to be My Worst enemies". Francis Chardon, in his Journal at Fort Clark 1834–1839, wrote that the Gros Ventres (ie. Hidatsa), "swear vengeance against all the Whites, as they say the small pox was brought here by the S[team] B[oat]." (Chardon, Journal, p. 126). In the earliest detailed study of the event, in The American Fur Trade of the Far West (1902), Hiram M. Chittenden blamed the American Fur Company for the epidemic. Oral traditions of the affected tribes continue to claim that whites were to blame for the disease. R. G. Robertson in his book Rotting Face: Smallpox and the American Indian, blames Captain Pratte of the steamboat St. Peter for failing to quarantine passengers and crew once the epidemic broke out, stating that while
  not guilty of premeditated genocide, but he was guilty of contributing to the deaths of thousands of innocent people. The law calls his offence criminal negligence. Yet in light of all the deaths, the almost complete annihilation of the Mandans, and the terrible suffering the region endured, the label criminal negligence is benign, hardly befitting an action that had such horrendous consequences.
  Some scholars who have argued that the transmission of smallpox to Native Americans during the 1836-40 epidemic was intentional, including Ann F. Ramenofsky who asserted in 1987: "Variola Major can be transmitted through contaminated articles such as clothing or blankets. In the nineteenth century, the U.S. Army sent contaminated blankets to Native Americans, especially Plains groups, to control the Indian problem." The Commissioner of Indian Affairs had refused to send the vaccine to the Mandans, apparently not thinking them worthy of protection.