 On 12 July, an American army under William Hull had invaded Canada at Sandwich (later known as Windsor).The invasion was quickly halted, and Hull withdrew, but this gave Brock the excuse he needed to abandon Prevost's orders.Having finally obtained limited support from the Legislature for his measures to defend the Province, Brock prorogued the Assembly and set out on 6 August with a small body of regulars and some volunteers from the York Militia (the "York Volunteers") to reinforce the garrison at Amherstburg at the western end of Lake Erie, facing Hull's position at Detroit.