The Sacred Buffalo Vision by Robert J. Juneau and Robert C. Juneau pg.22-23

Small-pox horrors" 
"The early part of the 1860's saw a devastating small pox outbreak among the various camps of the Blackfeet Tribe. By 1869 Chief Heavy Runner's band was suffering from a small pox outbreak at the time of Colonel Baker's massacre, and many of the Indians were dying from the disease when the soldiers fired into them, and burned them alive in their beds. Small Pox epidemics had resulted in destruction and demoralization of entire Indian tribes since the English colonists arrived in the Indian Country. William Bradford of Plymouth Colony conveyed some of the horrors of small pox in his description of the disease and its effects on the native populations: "A sorer disease cannot befall [the Indians] they fear it more than the plague. For usually they that have this disease have them in abundance, and for want of bedding and linen and other helps they fall into a lamentable condition as they lie on their hard mats, the pox breaking and mattering and running one into another, their skin cleaving by reason thereof to the mats they lie on. When they turn them, a whole side will flay off at once as it were, and they will be all of a gore blood, most fearful to behold. And then being very sore, what with cold and other distempers, they die like rotten sheep."
-The Sacred Buffalo Vision by Robert J. Juneau and Robert C. Juneau
pg.22-23