The Mohawks adopted him and elected him a sachem.
Within its limits from the upper Hudson westward to the Genesee river was the home of that powerful confederacy of Indian tribes, the Mohawks, Oneidas, Onondagas, Cayugas and Senecas, known to the French as the Iroquois and to the English as the Five (later Six) Nations.
A treaty of alliance with the Mohawks and Senecas procured for the English the same friendly relations with the Iroquois that the Dutch had enjoyed.
Even after the Peace of Aix-la-Chapelle (1748) the Iroquois complained bitterly of the fraudulent land speculators, and in 1753 the chiefs of the Mohawks threatened to declare the covenant chain broken.
Sir William Johnson died in 1774, but under his influence and that of his son, Sir John Johnson, and his nephew Guy Johnson, the Mohawks and other Iroquois Indians had become firmly attached to the British side and threatened the western frontier.
Returning from an expedition to Three Rivers he was captured by Mohawks, who tortured him and kept him as a slave until the summer of 1643, when, aided by some Dutchmen, he escaped to the manor of Rensselaerwyck and thence to New Amsterdam.