John Lichfield was Paris correspondent of The Independent for 20 years. Half-English and half-Belgian, he was born in Stoke-on-Trent and lives in Normandy.

Two sisters live next door to one another. Their relations, though friendly on the surface, have long been strained by mostly unspoken feelings of superiority or jealousy.

Then both sisters, tired of living with a succession of old men, marry new, young, ambitious husbands. In fact, one of the sisters, rarely able to make clear choices, takes two new husbands simultaneously.

These twin hubbies, Luigi and Matteo, are jealous of one another. They are also fascinated by, but wary of, the other sister’s husband, Emmanuel.

The various husbands, being young and ambitious, start to wash the dirty family laundry in public. The result: a stonker of a family quarrel, reminiscent of those seen in Italian movies from the 1950s. The neighbourhood is delighted but also alarmed. Where will this all end?

I speak of the great Franco-Italian quarrel of 2019.

The 2019 Franco-Italian war By Helen Thompson

On one level, it’s an absurd, sisterly spat which has long been in the making. It’s also a political manoeuvre before the European Elections in May, which are shaping up as the most interesting European elections since European elections began 40 years ago.

But it is also something deeper and, from a European Union viewpoint, darker – a skirmish which portends a wider war for the soul of Europe. Should the Europe of the 21st century be based on the supranational EU project which started over 60 years ago? Or should it revert to the much looser cooperation between nations which broke down so calamitously twice in the 20th century?

France withdrew its ambassador to Rome last week and, pointedly, reminded the world that this was the first time this had happened since Benito Mussolini declared war on France in 1940. It was also the first time since the creation of the EEC/EU in 1958 that one member state had withdrawn its ambassador to another.

There have been a series of jibes, insults and accusations hurled across the Alps in recent months. Most have come from the populist coalition government in Italy and its Number Two – really its de facto number one – Matteo Salvini, leader of the hard-Right Liga party. He accused the French, inter alia, of exploiting their ex-colonies in Africa and stealing their gold or dollar reserves to finance France’s debt. This is the kind of lie-by-exaggeration that Donald Trump might be proud of.

The 2019 Franco-Italian war By John Lichfield

Some of the insults have come from the centrist pro-European French President, Emmanuel Macron. He implicitly included Italy alongside Hungary and Poland when he warned of a “growing leprosy” of populist nationalism which threatened to destroy the EU.

He also said that the populist Italian government was “cynical” and “irresponsible” for closing its ports to African boat people. Then Mr Macron cynically refused to take a boatload of migrants himself.

In recent weeks, the junior leader of the junior Italian coalition partner, the country’s de facto number three, Luigi di Maio, joined the battle. He championed the Gilets Jaunes or yellow jackets, who have been campaigning, often violently, since mid-November to depose Macron and tear up the French constitution.

Last week he crossed a diplomatic Rubicon. Without informing the French government, he turned up in the outer suburban town of Montargis, south of Paris, for a photo-opportunity with a group of people whom he described as “the leaders of the Gilets Jaunes”.

Mr Di Maio, head of the anti-politics Five Star movement, praised the yellow vests as the French equivalent of his own party: a rejection of perpetual elites in favour of a popular government on the internet, by and for the grass-roots.

The 2019 Franco-Italian war By John Lichfield

Mr Di Maio had not done his homework properly. The group of half a dozen people that he met in Montargis were insignificant figures in an officially leaderless movement. One of them, Christophe Chalençon, is an obscure, far-Right activist who called last year for a military coup against Macron (and was disowned by other yellow vests).

The real leader of the breakaway group of Gilets Jaunes that Mr Di Maio thought that he was meeting is an impressive young auxiliary nurse called Ingrid Levavasseur. She plans to run a list of candidates in the European Parliament elections in May.

Madame Levavasseur was not informed of the Italian leader’s visit to France. She said that the meeting was “horrible”, a “total usurpation”, an unjustified invasion of French internal affairs and the work of a “world of sharks”, including Mr Di Maio. Several “spokespeople” for other tribes of the splintering and re-splintering Gilets Jaunes said roughly the same thing.

As a result, Mr Di Maio, was made to look ridiculous in the Italian and French media. His invasion of Gaul was supposed, Caesar-like, to shore up his weakening position at home in the uneasy coalition with Mr Salvini’s Liga party. The European elections are widely predicted to lead to early Italian parliamentary elections in the summer. If anything, Mr Di Maoio’s botched intervention has made him seem more feeble.

The 2019 Franco-Italian war By John Lichfield

In which case, did Emmanuel Macron and the French government overreact by withdrawing their ambassador to Rome? Maybe.

Part of Macron’s calculation was also electoral. His centrist La République En Marche party is vying with Marine Le Pen’s far Right Rassemblement National for top spot in the French part of the European poll on 26 May. Coming first in European Parliament elections has little practical significance, but would be an extraordinary mid-term triumph for a young president who has been battered by low opinion polls and street protests for months.

Just before the emergence of the Gilets Jaunes, President Macron had declared himself to be the champion of the supra-national European Union model of open markets and open borders, the rule of common laws and democratic values. He positioned himself as the man who would defeat the “anti-European”, nationalist-populist trend – or “leprosy” – which had taken power or a share of power in Italy, Austria, Poland and Hungary.

“Defeat” by Mme Le Pen in the European elections would be a bitter blow for Macron. By taking such a dramatic stand against Di Maio’s calculated – or miscalculated – insult, the French president hoped to galvanise pro-European opinion in France to take the European elections seriously (the usual turnout is around 40%) and vote for his party in May.

The 2019 Franco-Italian war By Helen Thompson

In any case, there were good reasons, or excuses, for France to take such dramatic action. Mr di Maio’s arrival unannounced on French soil to hob-nob with a violent dissident went beyond all the usual tolerated limits of interference by one EU government in the internal affairs of another. Such interference is banned by the EU treaties.

“But, but, but”, British Eurosceptics might well splutter, Macron interferes in British “internal affairs” all the time. On several occasions recently, he has spoken of the 2016 British referendum decision to leave the EU as “based on lies” and impossible to deliver because “you can’t deliver a lie or something that doesn’t exist”.

Isn’t that interference in a British internal affairs? No, not really. If Macron had turned up unannounced at a meeting of British Remainers in, say, Reading, and called for a second referendum, that would have been interference. His comments on Brexit – a subject of vital importance to France and the whole of the EU, not just the UK – were made at public meetings in France.

In any case, the whole of the French mainstream media, Right and Left, has supported Macron’s decision. Mme Le Pen has been left floundering. As a fierce French sovereigntist, should she praise Di Maio for sticking it to the pro- European Macron? Or attack Di Maio for invading France’s political space?

The 2019 Franco-Italian war By Matthew Goodwin

It is difficult to see where the row goes in the short-term. The two countries are bound together by centuries of shared history and culture, and profound economic integration.

Italy is France’s third-biggest market for exports. France is the second most important export market for Italy. French banks hold €285 billion in Italian debt – about a sixth of Italy’s staggering €2 trillion total (130% of its GDP). It is not in the interest of either country to destabilise the other.

Some of the quarrels between the two nations go back a long way. Others have been invented or revived by Salvini and to a lesser extent, until now, by Di Maio.

The finger-pointing on illegal migration started before Macron was elected in 2017 or the Italian far Right-populist coalition took power last year. There are now 5,000,000 foreign-born residents of Italy, compared to 1,300,000 in 2002. Most of the increase comes from absorbing African and Middle Eastern migrants who have crossed the Mediterranean from Libya.

Most other EU countries, and especially France, have been reluctant to share this burden. Salvini called Macron a “hypocrite” last year when he lectured the Italian government on their human rights responsibilities and then refused to admit a ship-load of migrants that was floating in the Med. Salvini also tweeted videos of French police blocking migrants at the French-Italian border.

The 2019 Franco-Italian war By Peter Franklin

There is more. Italy accuses France (starting long before the present incumbents) of picking off Italian business jewels but preventing Italian companies from buying French “champions”. The latest spat is over a Paris-willed, Franco-German challenge to the proposed takeover by Italy’s Fincantieri S.p.A of France’s Chantiers de l’Atlantique – the company which built the Queen Mary 2 and other state-of-the-art cruise liners.

Salvini has also explicitly spelled out long-standing Italian unhappiness with the budgetary rules which underpin the single European currency. He has blamed a “Franco-German axis” which ignores the interests of Southern EU states.

He was forced to back down in December and accept objections from Brussels to the Italian coalition’s attempt to increase unilaterally its agreed annual budget deficit. Cue Italian fury when France was allowed to exceed its limit this year to fund a €10 billion package of concessions in response to the demands of the Gilets Jaunes.

Salvini also accuses France of sheltering 15 Left-wing Italian terrorists, convicted in absentia for attacks on politicians in the 1970s. And there have been quarrels over Libya, a former Italian colony, where Rome accuses Paris of advancing its national interests.

Mr Salvini’s accusation that France subsidises its own debt by exploiting its own former African countries is rejected by most independent economists. Salvini also claimed that French exploitation of African countries was “causing” the migrant flow across the Mediterranean. In truth, few of them come from francophone countries.

The 2019 Franco-Italian war By James Bloodworth

There was even an unpleasant spat between the media of the two countries when France won the soccer World Cup last July. Italy had failed even to qualify for the finals in Russia. Some Italian journalists suggested that the multi-ethnic France team was not truly French.

Such quarrels are jealousies between EU countries, and have always existed. They did not begin with, or end with, the creation of the Common Market and then the European Union. The difference is that they have mostly been confined in the past to private rows between leaders and public rows in the press.

Salvini, and now Di Maio, and to an extent Macron, have brought these disputes into the open. In Salvini’s case, he has overstated them in emotive language, of the same kind he uses against domestic political foes in Italy. There are resemblances with Donald Trump’s attack-dog “diplomacy” against America’s allies.

Some commentators believe that this is a “good thing” for the European Union. For the first time, they say, it has created a political forum in Europe akin to that of a national stage. The political savaging of today will, they say, become the common European identity of tomorrow.

Alberto Allemano, 43, Italian-born professor of European integration at the internationally-respected French business school, HEC, says: “There is a Europeanisation of the political space. Is that a bad thing? I don’t think so. Usually, the European Parliament elections have been just a collection of national elections where voters expressed their approval or disapproval of national politicians.”

“For the first time, in 2019, two different visions of Europe will confront one another. The European elections will finally be about Europe.”

This is an interesting argument but may be overblown. Will the turn-out in the European elections really be higher? Will voters in France, or other countries, really base their votes more on European issues?

The 2019 Franco-Italian war By Peter Franklin

The darker interpretation of the 2019 Franco-Italian war of words is that the post-war consensus which created the EU is breaking down. These are, after all, two of the founding members of the Common Market, two of original Big Three within the original EEC Six of 1958.

To that you must add the nationalist, anti-democratic drift in Hungary and Poland. You must also add the growing nationalist and anti-Brussels feeling in other member states, including France. In a poll last week, 40% of French people said that they were like to leave the EU (Frexit). Some Gilets Jaunes are fiercely anti-Brussels. Others, such as Ingrid Levavasseur, are pro-European.

Paradoxically, the divisive forces within the EU have been weakened, or at least changed, by Brexit. The messy and contentious British withdrawal – the doubts about how, or even if, Brexit can happen – have discredited the full-frontal, anti-EU arguments in the 27.

But they have not gone away. Through Maldini, Di Maio, Viktor Orban, Marine Le Pen and others they are taking a new form. The Maldini/Le Pen argument is that the EU should be “reformed” from the inside, to make it a looser collection of trading states. For “reformed” from the inside, read dismantled from the inside.

The starting gun for that battle may have been accidentally fired last week in the small town of Montargis, south of Paris.