One of the resilient principles of Freudian analysis is the notion that the most enlightening and consequential disclosures are often to be found in the aside, the slip of the tongue, the remark made en passant.

In the Times Literary Supplement’s list of books of the year, the historian and biographer Richard Davenport-Hines rightly praises Max Hastings’s magisterial Vietnam: An Epic Tragedy 1945-1975. In the final sentence of his short review, Davenport-Hines observes that “Brexit is Britain’s Vietnam”.

His point, of course, is not literal. No bullets are flying, no napalm is being dropped, no protesting students are being shot. Millions died in the decades-long conflict that tore through Indochina — a far cry from the shouting matches and faction-fighting that have thus far characterised the Brexit saga. But — mutatis mutandis — the parallels are uncomfortably vivid.

As with Vietnam, so with Brexit —technology has played a central role in a story of division, dissent and disaggregation. In the Sixties it was the proliferation of television: towards the end of the conflict, the late Sir Robin Day wondered whether “in future a democracy which has uninhibited television coverage in every home will be able to fight a war”. To which the answer was: no, not like Vietnam.

In the great drama of Brexit — and the global rise of the populist Right of which it is a reflection — social media has been absolutely pivotal. We now know beyond question that digital technology was used illegally in the 2016 referendum campaign, and that the abuses were partly driven by foreign intervention.

Equally, social media has been the driving force behind the resistance to Brexit and the mobilisation of those who do not accept that a narrow victory in a single referendum mutilated by lies, unlawful tactics and foreign sabotage is a sufficient basis to transform the country’s constitutional, commercial and cultural arrangements.

Then, as now, public opinion changes. In October 1965, Gallup found that 64 per cent of the American public approved of US involvement in Vietnam. By January 1969, the figure had fallen to 39 per cent. The turning point was probably the Tet Offensive launched in January 1968 and Walter Cronkite’s remarkable televised verdict in February that “we have been too often disappointed by the optimism of the American leaders, both in Vietnam and Washington, to have faith any longer in the silver linings they find in the darkest clouds”.

Then, as now, trust plummeted as it became clear that the official narrative was very far from the truth. “Oh, man,” says Martin Sheen’s Captain Willard in Apocalypse Now, “the bulls**t piled up so fast in Vietnam, you needed wings to stay above it.” The same gift is required today — by all sides in the Brexit controversy. Leavers have grasped that Theresa May’s deal with the EU is nothing like what they demanded. Remainers see no point in embracing an agreement that would explicitly and indefinitely make Britain a rule-taker but not a rule-maker.

And, as in the US in the Sixties, the crisis has forced a perilous cantonisation of domestic debate. In particular I am struck by the angry generation gap that Britain’s scheduled departure from the European Union is nurturing.

"Those who dismiss young protesters as ‘snowflakes’ and ‘privileged Remoaners’ are wide of the mark"

When the movement for a People’s Vote was launched it looked embarrassingly like the liberal elite demanding its job back. Now it more closely resembles a grassroots uprising of the young against their elders. If you have not yet watched Femi Oluwole, the 27-year-old co-founder of Our Future Our Choice (Ofoc), taking on Brexiteers, you are missing out.

Ditto Will Dry, co-president of the same group, who voted for Brexit in 2016 but “changed my mind, very simply, because much of what the Leave campaign said would happen has not happened”. Go to YouTube and watch his rhetorical evisceration on Sky News of Robert Oulds, director of the Bruges Group — an object lesson in the power of impassioned, evidence-based argument against presumption and magical thinking. In this debate it is not the younger generation that is entitled and lazy.

With unexpected speed Brexit has become the ugly maypole around which the nation’s youth dances in fury — just as Vietnam was for their American counterparts in the Sixties. In The Vietnam War, the book inspired by Ken Burns’s astonishing PBS documentary series on the conflict, Todd Gitlin describes the anti-war uprising thus: “It was not a network of celebrities. It was a movement — a social force, a work in progress, an ensemble, confusing, contentious, irregular, raucous, immense.”

This is precisely what is happening — albeit on a smaller scale — in the rise of groups such as Ofoc and FFS (For our Future’s Sake), campaigns that played such a significant role in the People’s Vote march last month that drew 700,000 people to the streets of London.

There may be no draft to be dodged in this national crisis and no draft papers to be burned. But there was an eerie resonance at the weekend in Ofoc activists destroying copies of May’s deal with blowtorches, spray paint and shears. None of those involved in the stunt will be forced to flee the country, as so many US draft-evaders did in the Vietnam era, but the contempt is the same and speaks across the decades.

Those who dismiss these young protesters as “snowflakes” and “privileged Remoaners” are wide of the mark. Whatever happens between now and the official departure date of March 29, they will not forget — or easily forgive. There are only 121 days to go. But, as with Vietnam, the wounds that have already been sustained will take years, perhaps decades, to heal.