For the Western commentariat, Emmanuel Macron’s election signalled a retreat from 2016’s populist electoral insurrections.

So it may strike the British reader as bizarre that the darling of the liberal consenus agrees with Colonel Blimp that bringing back national service is a bloody good idea. Unlike the fictional former British army officer, who would no doubt have a very precise set of plans about how Captain Mainwaring would train a contingent of young Pikes to go off and retake the Empire, Macron has been unclear and inconsistent about what he wants.

On the campaign trail, he said he would bring back “compulsory military service” for French men and women between the ages of 18 and 21, because young people must have “an experience” of “military life”.

However, last month a parliamentary commission including deputies from Macron’s La République En Marche party put forward a completely different set of proposals. Schoolchildren would do a tiny amount of hazily defined civic public service; as young adults, they would be implored, although not forced, to join volunteering groups.

It fell to Macron’s defence minister Florence Parly to insist that the programme would indeed be both military and mandatory. But then the president made his own pronouncement, saying that it would definitely be compulsory. Young people would have to experience some nebulous “exposure” to the military, although they could mainly participate in civic organisations. After that, Macron quite openly said his government wouldn’t decide on the details until later.

The last thing France’s armed forces want is to use their already overstretched money and resources to give young people some ill-defined “experience” and compel the inevitable swathes of the reluctant. They have serious jobs to do on several fronts.

After years of budget cuts, they’re fighting in the Sahel and the Middle East while also patrolling the streets at home. Meanwhile, even according to the Macron’s generous projections, national service would cost 2-3 billion euros a year – on top of a one-off 15-20 billion euro “investment” cost.

So why is Macron so keen on it? His self-proclamation as a “Jupiterian” President is telling. This comparison of himself to the Roman king of gods evinces an ego the size of the planet Jupiter. That explains why Macron made such a grandiosely gimmicky campaign promise and is ploughing on with it despite clear signs that – in all of its suggested manifestations – it is a very bad idea.

But in the context of French history, it is not so strange that the paragon of liberalism advocates this nationalist policy. Political cross-dressing is a long-standing feature amongst leaders of L’Hexagone. In the fifties, it was Guy Mollet – a bien-pensant social democrat and supposed opponent of colonalism – who did most to plunge France into its mad attempt to cling on to Algeria. In the seventies, it was the cautious conservative Georges Pompidou who outraged his supporters by forcing through unseemly “modernisation” of Paris. Meanwhile, at the height of Cold War sabre-rattling in the eighties, it was François Mitterrand – with Communist Party members in his government – who brought Paris’ foreign policy closer to Washington’s than ever before.

Left-wing and centrist politicians worship the ideal of the French nation-state just as much as their right-wing counterparts. This, however, doesn’t seem such a contradiction in France. It’s not seen as just a nation-state, but as ‘the Republic’ forged in the Revolution. Ardent devotion to the nation is as much of the left as it is of the right. For example, Macron’s foremost parliamentary opponent, the hard left firebrand Jean-Luc Mélenchon, makes Corbyn look Blairite except for his full-throated French patriotism and zero interest in internationalism.

The army plays a key role in this Republican mythology. Le Marseillaise was originally written as “Chant de guerre pour l’Armée du Rhin” (“War Cry for the Rhine Army”). In singing their national anthem, the French are repeating its call to arms against the monarchist Austrian and Prussian invaders attempting to crush L’Hexagone’s nascent Revolution in 1792.

During the nineteenth century, it was the series of revived monarchies that repeatedly got rid of national service; the successive restored Republics then reintroduced it. In 1997, it was Jacques Chirac, of the centre-right, who abolished it for the last time.

An Anglo-Saxon stereotype about the French is that they are in thrall to abstract ideological concepts – like that of the Republic and the importance of giving young people “exposure” to it – while disregarding what works in the real world. As the old joke goes, they ask, “it may work in practice, but the question is: does it work in theory?”

But, Macron’s two grandest predecessors as President of the Fifth Republic thought ideologically but acted pragmatically. De Gaulle may have been captivated by notions of French imperial glory, but when he saw that European colonialism had become untenable, he decolonised. Likewise, Mitterrand may have been very fond of socialist economic theory, but when it put the economy in the tank, he did a 180 turn.

Unlike his more recent predecessors, Macron has some of the charisma of De Gaulle and Mitterrand. He would do well to learn from their pragmatism.