Henri de Tonti was a Frenchman of Italian descent. His father, at about the time Henri was born (circa 1650), fled to France after a failed uprising against the Spainish contingent in Naples.
Henri enlisted in the French Army in 1668 and later served in the Navy. He lost his right hand in a grenade explosion at Labisso during the Sicilian wars and substituted a metal hook, earning him the nickname of "Iron Hand".
de Tonti's name is usually said in the same breath as Robert Rene Cavelier, Sieur de La Salle. He was La Salle's main aide in exploring the Illinois River and was left in charge of Fort Crve Coeur near present-day Peoria when La Salle returned to Fort Frontenac on Lake Ontario in 1680.
In the spring of 1682 de Tonti accompanied La Salle on his exploration of the Mississippi River and one of the branches at its mouth.
After La Salle's death and intermittent skirmishes with Spaniards and Native Americans for the next 20 years, de Tonti contracted Yellow Fever and died in 1704.