 Perrot was financially ruined.He returned to Montreal, where in the spring of 1688 he served as an interpreter for the treaty between Governor and Onondaga chief Otreouti, who promised the neutrality of the Onondaga, Cayuga, and Oneida of the Five Nations of the "Haudenosaunee" or Iroquois League in confrontations with the French.In 1689 he built Fort Saint-Pierre at the mouth of the Wisconsin River, and established peace among area tribes.