The Sacred Buffalo Vision by Robert J. Juneau and Robert C. Juneau pg.15

"Montana Confederates massacre the Piegans" 
"The Blackfeet Indians felt they could stem the flow of the border-whites into Blackfoot Country, held by treaty with the United States. Guerrilla warfare between the ex-Confederate soldiers sent up the Missouri River by the Union Army and the Blackfoot Indians were the order of the day. 
John B. Morgan, a confederate squaw man, lived near the mission. He entertained four Piegan's at his house long enough to have his band of Confederates to capture the Indians while they were eating at this table. The Piegans were hanged from trees on Morgan's property and their bodies thrown into the river through a hole in the ice. This treacherous killing was immediately reported to the Piegans. John Morgan ran to the mission and begged the priests to allow him to live at the mission, lying about the killings and saying he was in danger owing to the unsettled conditions between whites and Indians."
-The Sacred Buffalo Vision by Robert J. Juneau and Robert C. Juneau
pg.15