[dash2]

I don't think they had a concept of collective salvation. They were very clear that salvation was individual, and that even people who thought they were saved, and who everyone around them thought was saved, might not be. I think you're right that they were strict about imposing their beliefs, at least in C17 New England, but I am not sure that relates much to their foreign policy wrt the Indian tribes. But I will defer to someone who knows more.

[thisiscorrect]

A very accessible book which discusses exactly the intersection of Puritan beliefs and their treatment of American Indians is "American Nations" (https://www.google.com/books/edition/American_Nations/Oc5VDw...).

https://www.chronicle.com/article/patriotism-and-the-puritan... is an essay on a related topic.