The War of 1812 having been officially declared by the United States on 18 June 1812, military operations took some weeks to follow.
On this day in 1812AD, the American army of William Hull (+1825AD), marching from Detroit, crossed into Ontario, Canada, marking the beginning of the ground operations of the War of 1812 and an American invasion of British Canada.
William Hull (Governor of the Michigan Territory, 1805-1813)
For the British and Canadians, Major-General Isaac Brock (+1812AD) was quite to exploit the slow advance of the American army that commenced on this date 200 years ago. While the American army was hesitant in its move into British territory, Brock moved decisively to deliver a counter blow to the American cause.
Sir Isaac Brock (+1812), the "Hero of Upper Canada"
Brock's capture of Mackinac Island on 17 July 1812AD, where he surprised a garrison unaware that war had been declared, forced Hull to abandon his invasion and fall back to Detroit in the Michigan Territory. Thus, by early August, the first American attack was over. On 8 August 1812, Hull withdrew the greater part of his invasion army back into American territory, taking refuge at Detroit.
William Hull, from a position of confidence, allowing for the invading of Ontario on 12 July, was, by August, rather concerned -- the tribes of the region were lining up in support of Brock and the British and Canadians, the planned American invasion of Quebec to distract the British was postponed, and British General Brock was upon him. He needed help, or Detroit itself could fall to the skilled Brock and his Indian allies...