The French presidency said it was an "important moment" for showing the relationship was "a bedrock which can relaunch itself ... in the service of reinforcing the European project".
"We're seeing an existential crisis in terms of European integration, with Brexit and the expected strengthening of nationalists at the next European elections," said Claire Demesmay, a political scientist at German research institute DGAP.
It also includes a "mutual defence clause" in the event of one of them being attacked, although they are already committed to this as members of NATO.
"Populism and nationalism are strengthening in all of our countries," Merkel told French, German and European officials gathered in Aachen's town hall.
Citing Britain's departure from the European Union and the growing protectionist tendencies around the world, Merkel noted that international cooperation is going through a rocky time.
"Seventy-four years, a single human lifetime after the end of World War II, what seems self-evident is being called into question again," she said. "That's why, first of all, there needs to be a new commitment toward our responsibility within the European Union, a responsibility held by Germany and France."
"We assume the commitment to develop a common military culture, common defence industry, a common line for arms exports. Thus, we want to contribute to the formation of a European army", Merkel said.
The renewed Elysee Treaty also focuses on Franco-German defense cooperation and the fight against terrorism — and here, the countries have already come a long way. A joint military unit, the Franco-German Brigade, was created in 1989. It has, however, lost some of its significance in recent years, and plays no major role in the countries' day-to-day military routines.
Moving from visions to concrete defense projects has always been difficult because of the nations' diverging philosophies: The French are more likely to opt for intervention, while the Germans are very reluctant on the military stage. That should improve, however, as Germany and France have pledged assistance — including military assistance — "in the event of an armed attack" on one of the two countries.
The European Union is moving towards an EU army despite repeated assurances down the years that such a scenario would never happen.
Macron continues to pursue globalist policies despite his popularity sinking to a paltry 23% and France being beset by violent protests for almost two months.
The signing of the treaty solidifies Angela Merkel’s commitment to globalism.
During an event aimed at combating populism entitled Parliamentarism in the Tension of Globalization and National Sovereignty last year, the German chancellor brazenly said that “nation-states should be willing to give up their sovereignty today” and this should be done via an “orderly process”.
The Aachen treaty calls for closer work - in defence and the economy, as well as cultural integration, however it has been met with dismay from politicians on both sides of the border.
Labelled as 'high treason' by one French MEP and labelled as a 'Macron-money grab' by Alexander Gauland from the AfD - the agreement is supposedly designed to inspire greater unity in a fracturing Europe.
The treaty calls for cabinet meetings between politicians from both countries at least four times a year as well as coordinated defence projects. it also stipulates French support for Germany sharing its seat at the UN Security Council.
Refugee policy appears not to have been specifically addressed, however.
A number of Yellow Vest protesters from Germany gathered, with one, Henrik, telling Sky News, “We are here to protest against Macron and Merkel because of the way they are changing Europe.
“This is not the idea of Europe. Europe is an economic platform that everyone can work together with — not the kind of Europe where leaders [tell us what to do].
“Countries have the right to say they want this or that, but not Europe.”
“I am against the way Europe is going right now. It’s not the way democracy works,” Henrik added.
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”.