From the Clarke Historical Library at Central Michigan University:
The Potawatomi Experience of Removal
In particular the Great Lakes region posed difficult military problems because of the possibility that the Indians might ally themselves with a hostile European power. ...the Great Lakes tribes had easy access to British Canada. The Indians of the region had largely sided with the British both during the Revolutionary War and the War of 1812.
In the Great Lakes region, the American government had to consider the unsettling possibility that should an Indian war occur His Majesty's army might directly or indirectly support the Indians.