© AP/Martin MeissnerFrance's President Macron and Germany's Chancellor Merkel after signing the Germany-France friendship treaty update
The French president, Emmanuel Macron, and German chancellor, Angela Merkel, signed the 16-page update to the 1963 Elysée treaty on Tuesday in the German border city of Aachen, the residence of Charlemagne, the "father of Europe" who managed to unite much of the western part of the continent in the ninth century.
With the EU under unprecedented pressure from Brexit, Donald Trump and nationalist governments in Italy, Poland and Hungary, Macron and Merkel sought to renew their nations' commitment to the bloc and limit the gains Eurosceptic parties are expected to make in European parliamentary elections in May.
"Populism and nationalism are strengthening in all of our countries," Merkel told French, German and EU officials at the ceremony. "Seventy-four years - a single human lifetime - after the end of the second world war, what seems self-evident is being called into question once more."
Macron said those "who forget the value of Franco-German reconciliation are making themselves accomplices of the crimes of the past. Those who ... spread lies are hurting the same people they are pretending to defend, by seeking to repeat history."
The text promises enhanced economic and security cooperation, including the aim of a "German-French economic area with common rules" and a "common military culture" that Merkel said could "contribute to the creation of a European army".
However, domestic far-right opponents in France and Germany said the document signed away national sovereignty, and Eurosceptics abroad derided it as a symbolic and irrelevant gesture by two significantly weakened leaders.
Marine Le Pen, the leader of France's National Rally party, accused Macron of "an act that borders on treason", while Alexander Gauland, of Germany's Alternative für Deutschland (AfD) said Paris and Berlin were trying to create a "super EU" within the bloc.
"As populists, we insist that one first takes care of one's own country," Gauland said. "We don't want Macron to renovate his country with German money ... The EU is deeply divided. A special Franco-German relationship will alienate us even further."
Italy's far-right interior minister, Matteo Salvini, said earlier this month that he intended to challenge the text's pro-European message, and indeed the whole idea of a "Franco-German motor", with a Eurosceptic "Italian-Polish axis".
Far-right opposition to the treaty has spawned a raft of conspiracy theories online, including the claim that Macron plans to cede control of Alsace and Lorraine, partially annexed by Germany in 1871 and returned to France after the first world war.
Others include the false claim that France aims to share its permanent seat on the UN security council with Germany, part of broader accusations that the centrist president was determined to "dismantle the power of our country", as Le Pen alleged.
Donald Tusk, the president of the European council, who attended the ceremony, said he would like to believe the treaty would "revive faith in the meaning of solidarity and unity", but Judy Dempsey of the thinktank Carnegie Europe said it "lacked strategic depth" and was a shadow of its 1963 forerunner.
"Maybe the expectations for France and Germany continuing to shape Europe have become too high," Dempsey said. "Maybe new groupings of countries, big and small, are needed to galvanise support for setting a strategic course for Europe."
Macron came to power in May 2017 promising to win Merkel's backing for major EU changes in an effort to restore confidence in the European project, but has made little progress, partly because the chancellor was herself weakened by poor election results.
Merkel has since announced she will step down as chancellor in 2021. The French president, meanwhile, has come under domestic pressure in the form of the anti-establishment, grassroots gilets jaunes (yellow vests) protest movement and plummeting approval ratings.
On closer security cooperation, France and Germany pledge in the text to come to each other's defence in case of military attack, create a joint defence and security council, harmonise their rules for military equipment exports and work together on procurement.
It comes after Macron last year urged the EU to reduce its military dependence on the US and called for a "real European army".
The treaty also promises a commitment to economic convergence, to set up a panel of experts to give economic recommendations to each government, and to boost research cooperation in the digital economy and renewable energies.
Finally, the treaty seeks to strengthen concrete ties across the 280-mile (450km) Franco-German border, supporting city partnerships and bi-national initiatives in culture, health, transport and language-learning, with some cross-border regions to be granted greater autonomy to cut through rules and red tape.
Comment: This 'pact' - a politically calculated and aggrandizing move by fading leaders M&M - is instead garnering repercussions of polarization and divide.