Obviously they got it from the blankets the Indian Agent gave them. Darn White Man!
The old Blanket myth again. It keeps making the rounds.
https://www.historynet.com/smallpox-in-the-blankets.htm
(Howard Beale “I’m mad as hell and I’m not going to take this anymore.”)
“When you’re slapped you will take it and like it!”-Bogart to Joe Cairo (Peter Lorre in Maltese Falcon)