In October 1814, an invading American force of about 700 men under Brigadier General Duncan McArthur advanced rapidly as they left Detroit and raided the Thames Valley. The plan was to devastate the Grand River settlements and the region around the head of Lake Ontario which supplied British forces on the Niagara frontier. The Canadian militia in the region was caught unaware by this swift raid from the west, and McArthur's force continued east at a fairly rapid pace, arriving at Brant's Ford on the Grand River on November 5.