The explorers finish building the fort in…
March 1680 CE
The explorers finish building the fort in early March, naming it Fort Crèvecoeur ("Fort Broken Heart") because of the tribulations, including desertions, that they have suffered during its construction.
Fort Crèvecoeur will later lead to the development of present-day Peoria, Illinois.
La Salle sets off on foot for Fort Frontenac for supplies.
While he is gone, Louis Hennepin follows the Illinois River to its junction with the Mississippi.