This year, American troops will join their French allies in the annual parade, to mark 100 years since the US intervened in World War One.

It is not every president who can resist a military parade, especially one with a bit of revolutionary fervour thrown in.

And two months after sweeping aside France's old political order in his bid for the presidency, who better for Emmanuel Macron to invite to his first Bastille Day parade than another political revolutionary from across the Atlantic?

Especially as this year's parade comes with the added benefit of refocusing attention away from their current personal and political squabbles on to a time when French and American soldiers fought side by side for common values.

Solidarity seems harder these days.

In fact, few allied leaders have managed to pack so much antagonism into such a short relationship.

When the two first met ahead of a Nato summit in May, President Macron treated the US leader to a gripping handshake in front of the cameras, which he then refused to release for several long moments.

He was seen as snubbing President Trump again later in the summit, when he appeared to swerve away from Mr Trump's open arms, making the US president wait while he greeted other leaders first.

President Trump then announced he was pulling out of a key climate change agreement brokered in Paris, which prompted Mr Macron to release a video, in English, inviting US scientists to come and live France, and parodying the Trump campaign slogan with a call to "Make Our Planet Great Again".

Perhaps it is not surprising that things have been difficult between them.

Both men see themselves as unconstrained by the old style of established politics, both are keen to portray themselves as strong leaders, and there are real political differences too.

'Juvenile rivalry'

Mr Trump openly supported Mr Macron's far-right rival Marine Le Pen during the French presidential election, and allegations over possible Russian influence in both the US and the French elections hang heavily over this visit.

Nevertheless, at times, they almost seemed to be enjoying their little PR feud.

"It is high time to finish with the juvenile rivalry of handshakes," said an editorial in Le Monde last month. Mr Macron may have "stolen the American president's monopoly on being unpredictable…. [but he] wants to become the European leader of the international political scene. To achieve this, he'll have to go beyond images and symbols."

Mr Macron is good at flattering world leaders, and he has made more of an effort recently to woo Mr Trump.

The young, inexperienced French president has been keen to increase France's influence on the world stage - and boost his standing at home, where political loyalties are still divided.

The secretary-general of the Socialist Party, Jean-Christophe Cambadélis, told a French newspaper that Mr Macron was "looking for the company of the world's big leaders" because he needed to "legitimise his victory", having secured less than a quarter of the vote in the first round of France's presidential election.

Having already hosted Russian President Vladimir Putin at Versailles, Mr Macron will now treat his American counterpart to an old-fashioned display of pomp and military might.

Tight security a year after Nice attack

Mr Trump's acceptance of the invitation is a chance for him, also, to showcase transatlantic ties and highlight the shared challenges nestled alongside the two countries' disagreements: the conflict in Syria, the military alliance, and the fight against terrorism.

Friday's commemorations will be a poignant reminder of the terrorist threat here, marking one year since France's last major attack, in Nice.

Eighty-six people were killed in that attack, when a Tunisian-born man drove through crowds gathered to watch Bastille Day fireworks on the Promenade des Anglais. President Macron is due to fly down to Nice later on Friday to take part in the commemorations there.

Security around the event in Paris has been boosted this year, with Mr Trump's attendance adding an extra dimension to preparations in the capital.

It is a visit showcasing the many sides to Franco-American links: past victors, future allies, current targets.