Dark was the wilderness

the long version

I read a book by this name when I was about 12. If this is the same book, it's a fictional account of Isaac Jogues, Jean de Brebeuf, and several other French Jesuits who came as missionaries to the Huron Indians. They were eventually tortured and killed by Iroquois and Mohawk Indians, who were enemies of the Hurons. It inspired me to want to be a missionary. The group is sometimes called the North American Martyrs.