The decision of his enemy “could not be reconciled with reason,” once mused a great statesman. “I felt sure she would be ruined for a generation by such a plunge, and this proved true. But governments and peoples do not always take rational decisions. Sometimes they take mad decisions. Or one set of people get control, who compel all others to obey and aid them in folly.”

Any takers, Balliol College, Oxford? No? It’s Winston Churchill, considering why Japan, already mired in an unwinnable campaign in China, would “court destruction” by going to war with Britain and the US in 1941. “I have not hesitated to record repeatedly my disbelief that Japan would go mad,” Boris Johnson’s idol wrote in his history of the second world war. “However sincerely we try to put ourselves in someone else’s position, we cannot allow for processes of the human mind and imagination to which reason offers no key.”

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I came across this fun insight while trying to take my mind off Brexit, by doing a spot of ironing to Dan Carlin’s Hardcore History podcast about the Asia-Pacific war of 1937-1945. But Brexit has a habit of worming its way back into your brain: the Baby Shark song of constitutional crises. I’m not saying that the pickle Britain is in is comparable to the situation in Japan in 1941. I can’t quite see Jacob Rees-Mogg masterminding a scheme to catch the Belgian fleet at port, and the ensuing chain of events leading to a multiple-front war, ending with the nuclear annihilation of Sheffield and Bristol.

I’m merely saying that history provides many examples of countries taking irrational, destructive courses and getting punished for them. It is just about possible for us in 2019 to follow the symphony of emotion that has led to 28% of British voters believing an act of economic self-sabotage will prove some sort of point; to firms from BMW to Panasonic shifting investment out of the UK amid the uncertainty; to Boris Johnson responding to such concerns with “fuck business”; to an MP whose whole argument was about British sovereignty asking an authoritarian rightwing government in Poland to help him overturn sovereign decisions of the British parliament; to no one even pretending Brexit will be beneficial any more, merely character-building. But in the not too distant future, these themes will fade, the ins and outs will be forgotten and people will say: “The decision could not be reconciled with reason.” The urge to Brexit never could; that’s an important lesson.

Another is that a conviction that you will prevail because your country is uniquely amazing (quite strong in Japan in 1941, I understand) is no protection against catastrophe. Indeed, it is much more likely to lead you towards it. This is a point that seems lost on leavers – history fans though they profess to be. Many have invoked our great imperial past as something we were destined to return to post-Brexit. In the giddy aftermath of the vote, Andrew Roberts thought that “one of the many splendid opportunities” offered by Brexit was the resuscitation of Churchill’s dream of a CANZUK union, comprising Canada, Australia, New Zealand and us. There was talk of Empire 2.0.

These days, the vibe is more “let them eat turnips”; Britain as underdog as opposed to would-be oppressor. However, a nasty strain of exceptionalism remains the default mode of the Brexit elite, usually abetted by a woeful misunderstanding of the qualities that have actually helped the British people in the past.

Earlier this week, the pro-crashing-out economist Roger Bootle told the Bruges Group that the reason Britain could never make its peace with the EU was that we are one of only four European countries not to have endured occupation or dictatorship this last century. How conveniently he forgets that Ireland and Malta have indeed spent much of their history under occupation – British occupation. And how cleverly he reframes geography as a matter of virtue rather than luck. An old trick of the ruling classes, to confuse virtue and luck.

It is not healthy patriotism that underpins that leave project but its toxic inversion: a hatred of Britain as it actually is, a contempt for its young, a dismissal of its businesses and an eagerness to make the poorest pay. Brexit hardliners are invariably the ones with dubious links to overseas pressure groups, with asset funds in emerging markets, with schemes to move their HQs abroad. The British reputation for pragmatism, good business sense and moderation is not some God-given destiny; it required some active application of the same qualities. It required some sense of responsibility towards the next generation. These are supposedly conservative values, but they were sold off a long time ago, the proceeds half-forgotten in a vault in the Cayman Islands.

Sadly, collective insanity isn’t necessarily a vulnerability in one’s opponents. Churchill again: “Madness is, however, an affliction which in war carries with it the advantage of surprise.”

• Richard Godwin is a freelance journalist