French President Emmanuel Macron and German Chancellor Angela Merkel have left their own mark of reconciliation at the start of events to mark the centenary of the end of World War One, reports BBC News.
They signed a book of remembrance in a railway carriage identical to the one in which the 1918 Armistice was sealed.
US President Donald Trump is among world leaders attending the events.
But Mr Trump caused controversy by cancelling a trip to a US cemetery on Saturday because of bad weather.
The day had a tense beginning amid a row between Mr Trump and Mr Macron over European defence.
The French leader said the EU needed a joint army now that the US was pulling out of a key disarmament treaty with Russia.
Mr Trump described the comments as insulting and said Europe should pay its share of costs within Nato, the Euro-Atlantic alliance.
After a meeting at the Elysée Palace, Mr Macron said he agreed that Europe should pay more.
Mrs Merkel became the first German leader since World War Two to visit the forest near the town of Compiègne in northern France where the Armistice was signed.
She and Mr Macron unveiled a plaque to Franco-German reconciliation, laid a wreath and signed a book of remembrance in a railway carriage similar to that used 100 years ago.
The moment was doubly significant because Adolf Hitler used the original carriage to accept France's capitulation to Nazi Germany in June 1940.
Around 70 world leaders are gathering in Paris for the events.
Mr Macron will lead the main event of the centenary - a sombre commemoration on Sunday at the Tomb of the Unknown Soldier, a memorial to France's fallen under the Arc de Triomphe in Paris.
Sunday afternoon will see Mr Macron and Mrs Merkel attend a peace conference - the Paris Peace Forum - with leaders including Russian President Vladimir Putin and Turkey's Recep Tayyip Erdogan.
After an hour of talks with Mr Macron and lunch with their wives Melania and Brigitte, Mr Trump had been due to visit one of two American cemeteries on his schedule.
But he cancelled his trip to the Aisne-Marne American Cemetery and Memorial due to "scheduling and logistical difficulties caused by the weather".
White House officials later explained that low cloud would have prevented his helicopter from landing, and cited security concerns about arranging a motorcade to the site.
General John Kelly, the White House chief of staff, attended on the president's behalf.
The decision attracted much derision on social media, including from President George W Bush speechwriter David Frum who, like many, drew comparisons with the conditions faced by the troops who fought and died in World War One.