[Don W]

The war of 1812 was a response to the US invasion of Upper Canada and the burning of York (then the Capital city of the nascent Canada).

[Mr. Lucky]

You were probably just trying to get someone's bobber down, but the US Declaration of War was signed on June 18, 1812, and contained a recitation of the depravations of USA sovereignty by Great Britain which necessitated it.

The invasion of Canada followed a month later..