Overall, Tecumseh's confederacy played a crucial role in causing the War of 1812, and in early operations in the west. In 1812 Tecumseh's warriors, as shock troops, assisted a small force of 700 British regulars and Canadian militia to force the surrender of 2,500 American soldiers, by threatening to massacre any captives of the Siege of Detroit. General William Hull surrendered Fort Detroit in August 1812 without a fight. Tecumseh's frontier war forced the Americans into rearguard actions, which divided their forces and prevented them from concentrating large enough numbers to successfully invade and occupy the strategically important area of Lower Canada (Quebec).