On 17 July, a mixed force of British regulars, Canadian fur traders, and Indians captured the important trading post of Mackinac Island on Lake Huron from its small American garrison who were not aware that war had been declared. Many of the Indians who had taken part in the attack either remained at Mackinac or returned to their homes, but 100 or more Sioux, Menominee, and Winnebago warriors began moving south from Mackinac to join those already at Amherstburg, while the news induced the previously neutral Wyandots living near Detroit to become increasingly hostile to the Americans. Hull learned of the capture of Mackinac on 3 August, when the paroled American garrison reached Detroit by schooner. He feared that this had "opened the northern hive of Indians" and so abandoned all the Canadian territory that he held.