PARIS — Britain may have declared its "independence" on June 23 but the soldiers of one of its elite military units are about to start taking orders from a Frenchman.

Within the next few months, an as-yet-unnamed French brigadier general will be appointed deputy commander of the British armed forces’ 1st (UK) Division in York. Some time later, a British officer of the same rank is poised to become deputy commander of the French first armored division.

British voters didn’t hear much about that historic swap during the referendum campaign, even as they were warned about a supposed secret project to build a “European army” hatched by Brussels bureaucrats. But it wouldn't have mattered even if Leave campaigners had decided to make it an issue: French-British military cooperation, anchored by the 2010 "Lancaster House" treaties, is set to increase in coming years and is unlikely to be much ruffled by Brexit.

That, at least, is the consensus for the near future. French and British diplomats say the bilateral agreement to increase cooperation between both countries’ military establishments — from politicians and generals to industrialists — is moving forward, even post-Brexit.

In the longer term, diplomats and security experts see a risk that the partnership — which was based on the idea that France and Britain, the only true European military powers able to project force abroad, can trust each other on the most sensitive of issues — could be affected by a souring of overall relations between the U.K. and the rest of Europe.

“Formally nothing changes with Brexit,” said Camille Grand, head of the Paris-based Fondation pour la Recherches Stratégique, adding that the Franco-British treaties have little to do with the EU. “Both countries have a vested interest in pursuing their implementation.”

“This is a day-to-day, intense partnership that has never been affected by whatever French or British-bashing was going on in either country in the last five years”— Claire Chick

For the last six years, the alliance has become routine between the two countries’ military establishments — moving forward largely under the political radar.

“This is a day-to-day, intense partnership that has never been affected by whatever French or British-bashing was going on in either country in the last five years,” said Claire Chick, head of defense at the Franco-British Council in London.

The French and British defense ministers meet once a month, amid countless meetings of military and civilian experts, industrialists and scientists from both sides. The two countries now have an operational joint action force — the setting of which necessitated working out such minute details as soldiers' ignorance of their colleagues' language and the French preference for written orders, different from the U.K.'s oral tradition.

But the treaties — one on military, the other on nuclear cooperation, both signed for 50 years by David Cameron and then-French President Nicolas Sarkozy — mostly look Brexit-proof. That's because they were aligned with both countries’ strategic, industrial and financial interests.

Stronger in?

Pooling resources in a time of austerity was seen as a means for both of Europe’s nuclear powers to keep a global military standing commensurate with their aspirations. That was made possible by the gradual fading of decades-old divergences and mistrust between Paris and London. The French had rejoined the North Atlantic Treaty Organization as a full-fledged member after 43 years; and the new British government was getting closer to Europe after William Hague, who would later become foreign secretary, called for a “solid but not slavish” relationship with the U.S. during the 2010 U.K. general election campaign.

The Lancaster treaties were rooted in pragmatism — in sharp contrast to another Franco-British initiative that Tony Blair and Jacques Chirac had undertaken in 1998 by signing the so-called Saint-Malo declaration. The mood back then, with a British premier who didn't hide his enthusiasm for all things European, was about making grand political and strategic aspirations with the aim of shaping the whole EU defense policy. The agreement produced some limited results but ultimately didn’t change the rules of the game in European defense.

The agreement by Cameron and Sarkozy 12 years later focused less on grand statements and more on action. On the military front, the Lancaster treaties initiated the launch of joint programs, such as tighter cooperation on naval warfare, research on the next generation of fighter aircraft, and the joint deployment of ground troops. After six years of preparation, the Combined Joint Expeditionary Force became operational last April, with the aim of mobilizing up to 10,000 troops for a range of operations either NATO-sanctioned or strictly bilateral.

The nuclear treaty set up a 50-year cooperation that sees both countries investing in huge computing capabilities to experiment on warhead material and equipment they both can use — albeit separately.

The political changing of the guard in France in 2012 did nothing to slow the rhythm of the treaties’ implementation. Socialist François Hollande picked up where conservative Sarkozy had left off. Last April Hollande and Cameron — as the Brexit campaign was in full blast — even launched a new series of bilateral projects.

Political clouds

However strong the reasons for the Entente Militaire to continue its forward march, politics may soon intrude.

“The Lancaster Treaties were predicated on Paris and London trusting each other in strategic matters after years of divergences and rivalries,” said one French diplomat.

That's no longer a given, especially if a drawn-out Brexit negotiations process starts to get ugly.

Another possible unknown related to the British vote, said François Heisbourg, the chairman of London-based International Institute for Strategic Studies, is the renewed possibility that Scotland will secede from the U.K. The U.K.’s only naval base for the country’s Trident nuclear submarines is in Faslane, northwest of Glasgow, and London might have to negotiate a deal with an independent Scottish government if only to buy the time to build another base. “That might at least throw some doubt on the nuclear modernization program agreed with the French,” Heisbourg said.

France isn’t insisting any longer on the absolute priority of Europe defining its own strategic identity. “I don’t speak of European defense, I speak of the defense of Europe,” French Defense Minister Jean-Yves Le Drian once quipped. As for the British, France’s return to NATO's military structures has assuaged longstanding fears that Paris harbored designs to circumvent the alliance.

The Pentagon likes the arrangement, too. A European diplomat said the Franco-British relationship has always been warmly supported by the U.S., for good reasons. Washington sees two European allies willing to increase their defense commitments who have stopped shrinking their defense budgets. France’s, for one, is still hovering slightly below the 2 percent of GDP pledged by NATO members, but Hollande put an end to years of defense cuts last year. France’s military spending is on track to overtake Russia’s in the next couple of years, according to Jane’s 360. The British government similarly decided in 2015 to spare defense from its general austerity policy.

No one knows what the next British government will look like, or when or if or how a Brexit from the EU will play out. But the U.K. remains shackled to its defense commitments. Staying a full-fledged, committed member of NATO, while being anchored to the continent by its French alliance, and possible future collaboration between the two countries and Germany, amounts to what a French defense ministry adviser called “a lock of mutually intertwined interests” that any government would “find hard to pick.”