This entry is for the township itself, for the island, see Grosse Ile (island).
As far back as 1718, a memoir belonging to the establishing Indian tribes on the Grosse Ile territory (the Fox, Sacs, Kikapoos and Potawatomies among them), it was stated there were long-lingering doubts whether Antoine de la Mothe Cadillac's Fort Detroit should instead have been founded on the island called Kitcheminishen. The apparent reason for this idea's hesitation was apprehension that "the timber would some day fail."
Two days after signing the Declaration of Independence (July 6, 1776), the territory of present-day Grosse Ile Township was sold to brothers, William and Alexander Macomb, by a grouping of various Indian tribes, which included the Fox, the Sacs, the Kikapoos and the Potawatomies. Secretary of State (and future President) James Monroe was among the signers. Historians assume that the Macomb brothers believed that, by purchasing this deed through the transfer of items of value, they had in fact obtained full ownership rights. In any case, the Macomb brothers are considered to be the founders, and first legal owners, of Grosse Ile; this is because the Potawatomis, and later the United States Government, respected the Macombs' perceived rights to take possession of the island.
9601 Groh Road