By most historical accounts, the War of 1812, the last time Canadians and Americans fought each other on the field of battle, was an eminently pointless affair — not merely “pointless” in the sense the pacifists call any military engagement “pointless,” but truly, strategically, tactically and militarily, pointless.

One-hundred-and-thirteen years later, America seems poised to engage in a similarly pointless trade war with what used to be called British North America.

The on-again-off-again tariff fight President Donald Trump is picking with Canada is a good reminder of just how dangerous it can be to forget principles. The definitive case against tariffs was made around 250 years ago by Adam Smith, crystallized by David Ricardo about a quarter-century later, and hasn’t been eroded much since. If anything, one would think that the disastrous effect of Smoot-Hawley in the 1930s would only have solidified the argument.

And yet here we are. This time with a Republican president intoxicated on the liberal economic myth protectionist tariffs ignite domestic productivity. The deficient economic reasoning aside, one vexing problem is quite a few of those “protected” American manufacturers make things rely on other things imported from places like Canada. One somewhat sobering example is the propellant used in artillery shells, currently made exclusively in a plant in Ontario.

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The concept of free trade is the soul of free market capitalism. If John can make shirts better and more efficiently than David, and David is more skilled at fixing machinery than John, it makes economic sense for John to make David’s shirts and David to fix John’s machinery. Any governmental intervention in that formula creates a market inefficiency and an artificial misallocation of resources.

Of course, retributive governmental action is in order when an act of economic aggression has been engaged in — where a disinterested third-party observer could reasonably conclude such an act occurred. OPEC in the 1970s, for instance. Certainly much of what the People’s Republic of China does on a regular basis can reasonably be argued to reach that standard. Two things: first, in such a case the reasonable mechanism for political reprisal is embargo, not tariffs. Second — what economic aggression has Canada engaged in? Sure, the Canadian dairy industry is pretty much the closest thing to communist practice in the Western world, but much of that was ameliorated by NAFTA and the Harper government, so that pricing system mostly hurts Canadians, and Canadian milk does not pose much of a threat to Wisconsin’s dairy farmers in any case. Softwood lumber is a perennial issue, but hardly rises to the standard of “economic aggression.”

So if there is no particular economic threat to be countered, what is the point? Is it to force some concessions from the Candidan government? On things like increased defense spending, restrictions on laissez faire immigration policies, hammering down on fentanyl and other drugs, or a harder line on communist China?

Well, if so, this tactic has the chance to backfire spectacularly. Such reforms would come as a matter course in the event a Conservative majority government led by a Conservative Canadian prime minster were to come to power in Canada — something that a couple months ago was as close to being assured as anything can be in democratic politics. Prime Minister Justin Trudeau was justifiably reviled by the majority of the Canadian electorate. His replacement, Mark Carney, is not much better. He has degrees in economics from Harvard and Oxford, which is on the order of receiving a degree in virology from the Robert F. Kennedy School of Medicine, and managed to make a royal mess of Great Britain’s economy as head of the Bank of England. His policies are virtually indistinguishable, and just as damaging, as Trudeau’s. The Conservative leader, the bright and talented Pierre Poilievre, was on track to win a landslide majority later this year.

Well that’s all been buggered right up. Trump’s ridiculous tariffs, and incessant “51st state” provocations have united Canadians to a remarkable level against their traditionally best global friend, wartime comrade and trading partner. Carney does not need to say a single word about policy — all he has to do is say “Trump” as often as possible, and paint his opponent as pro-American.

So, again, what will this manufactured trade war accomplish? If nothing else, it could needlessly shepherd an antagonistic government up north, and the economic repercussions here could erase any positives gained from reducing the size of government elsewhere. Abandoning free market principles and moving to the left of Bernie Sanders on trade will cause damage on both sides of the border that could take years to repair — rather like Washington D.C. after the War of 1812.

Kelly Sloan is a political and public affairs consultant and a recovering journalist based in Denver.