Le Sueur came to Canada with the Jesuits to their mission at Sault Sainte Marie, but very soon he turned himself to fur trade and became a coureur des bois.
Le Sueur returned to New France to mine this ore, but was waylayed by, among other things, a prison term for overreaching his trade privileges.
In 1699, he was with the group that ascended the Mississippi River from Biloxi to the "country of the Nadouessioux", stopping to overwinter at Isle Pelée or Fort Perrot above Lake Pepin.
After trading with the local Dakota bands (the Mdewankantons, Wahpetons and Wahpekutes) in the area, in the summer and fall of 1700 he and a group of 20 men went further up the river known to the native population as "minisota", or "cloud reflected water".
The group continued to the Blue Earth River, where they built Fort L'Huillier, named for the chemist who declared it to be copper ore.