Jo Johnson, the pro-Remain minister of transport, resigned from the government last week because he could not vote for the Brexit deal that Theresa May is expected to bring back to parliament. He thinks her deal is worse than membership of the EU and he has thrown his weight behind a second referendum. His resignation came four months after his Brexiteer brother, Boris, quit as foreign secretary.

The resignation of the two brothers is emblematic of the deep divisions over Brexit in the Conservative Party, the government, and the country at large. But the two brothers are strikingly different both in style and in substance. Boris is an unprincipled, irresponsible, buccaneering politician driven by a naked ambition to get to No 10. Jo is a calm and thoughtful statesman who places the national interest above that of his party. His purpose is not to change the leadership, but the policies. And he is able to place the current crisis in a wider historical perspective.

In his letter of resignation to the prime minister, Jo Johnson claimed that the public is being offered “an agreement that will leave our country economically weakened, with no say in EU rules it must follow and years of uncertainty for business” or a no-deal Brexit “that I know as minister of transport will inflict untold damage on our nation”.

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The letter went on to say: “To present the nation with a choice between two deeply unattractive outcomes, vassalage and chaos, is a failure of British statecraft on a scale unseen since the Suez crisis”. The reference is, of course, to the Suez crisis of 1956 in which Tory Prime Minister Anthony Eden colluded with France and Israel to attack Egypt following President Nasser’s nationalisation of the Suez Canal.

Suez was a colossal strategic blunder and a sad watershed in post-war British history. The difference between Suez and Brexit is that the former involved the use of force and the latter does, not. On the other hand, both crises posed a huge challenge for British statecraft. Some lessons might, therefore, be learned today from the failure of British statecraft back in 1956. As Churchill once observed, the farther back you go, the farther forward you can see.

The broader context for both crises was uncertainty regarding Britain’s place in the world. Eden, observed a Sunday Times editorial on January 16, 1977, “was the last prime minister to believe Britain was a great power and the first to confront a crisis that proved beyond doubt that she was not”. Eden was an imperial-minded politician, out of touch with reality, and Suez was a throwback to Palmerstonian gunboat diplomacy. In the end, Eden managed to combine immorality – disregard for international law, political folly – collusion with the Israelis, and incompetence – failed execution of a military operation.

The Suez war was indisputably a fiasco; the only debate is about the causes of the fiasco. Here, there are two main schools of thought. One school of thought sees the Suez debacle as the result of a loss of nerve, a failure of imperial willpower. According to this school of thought, the real mistake was not to embark on this venture but to abandon it without achieving its basic aim: the overthrow of Nasser. Once Britain retreated, so the argument ran, any monkey was free to twist the lion’s tail. A leading proponent of this view was Professor Elie Kedourie of the London School of Economics.

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The other school of thought, to which I belong, views Suez as a sordid colonial conspiracy and an act of imperial madness. It stemmed from an inflated belief in Britain’s ability to impose its will on the rest of the world. Indeed, it was little short of insane to resort to military force when there was a credible diplomatic option for resolving the dispute over the Suez Canal. Nasser was not “Hitler on the Nile”, as Eden portrayed him, Egypt was not Nazi Germany, and the lessons of “appeasement” from the 1930s did not apply. The decision to attack Egypt was a serious error of judgement, an act of hubris, and a self-inflicted wound.

So is Brexit. For the Suez misadventure, Eden paid the price: his career came crashing down in flames. For the country as a whole, however, the damage was limited. Suez was not the cause but a reflection of Britain’s descent from the summit of world power. It may have even had one positive effect: it acted as a reality check on Britain’s image of itself as a great power.

Like Eden, today’s Tory Brexiteers are incapable of grasping the changes that have occurred in the international system since 1945 and the limits they place on Britain’s ability to pursue an independent foreign policy. The notion of global Britain prospering outside the EU is a delusion based on ignorance and fuelled by nostalgia for the good old days of empire.

The consequences of leaving the EU either on the terms currently contemplated or with no deal at all would spell a disaster for this country on an infinitely bigger scale than those of Suez. The blame for this sorry state of affairs lies not with Theresa May but with the reactionary and xenophobic wing of her party. It is they who are pushing her towards a hard Brexit which would be much worse than the status quo.

The damage to Britain’s reputation as a result of the way the negotiations have been conducted since the referendum is already very considerable. The economic and political damage of actually leaving the EU would be massive and irreversible.

Britain used to be a well-respected country. Boris Johnson and his fellow Brexiteers have helped to turn it into a joke. Jo Johnson is surely right: we should pause on the brink, think again, and allow the public to revisit the 2016 referendum in the light of what has been learned in the last two years and the wider lessons of history.

The views expressed in this article are the author’s own and do not necessarily reflect Al Jazeera’s editorial stance.