War!
By Be it enacted by the Senate and House of Representatives of the United States of America in Congress assembled, That war be and is hereby declared to exist between the United Kingdom of Great Britain and Ireland and the dependencies thereof, and the United States of America and their territories; and that the President of the United States is hereby authorized to use the whole land and naval force of the United States to carry the same into effect, and to issue to private armed vessels of the United States commissions or letters of marque and general reprisal, in such form as he shall think proper, and under the seal of the United States, against the vessels, goods, and effects of the government of the said United Kingdom of Great Britain and Ireland, and the subjects thereof.
If you note any Britons, Canadians (or suspected Canadians) or (especially) Irish, make sure to have them arrested, interrogated, and possibly beaten. They hate us for our freedom, after all. Also, if you happen to have a boat this is an ideal time to begin seizing British and Canadian property on the high seas (or Great Lakes, if you prefer).