Emmanuel Macron becomes French President. Illustration / Rod Emmerson
They waved French flags, cheered and jumped for joy as the result they had hoped for flashed up on giant screens in the courtyard of the Louvre museum.
A packed crowd of thousands of Emmanuel Macron's supporters gathered beneath the statues on the museum's ornate facade, near the glass pyramid where tourists enter the Louvre, under a huge poster of the Mona Lisa.
The party is very much in the image of Macron himself and like him, it is the first time many of its candidates are running for public office. Herv Le Foll, a marketing and communications executive, said he hoped the election of France's youngest head of state since Napoleon would mark "a turning point".
Le Foll, 47, who voted for the outgoing Socialist President, Franois Hollande, in the last election in 2012, said: "Our generation saw the Berlin wall come down and we were joyful. Then we saw the rise of the Front National and we were afraid. Now I'm relieved and I'm glad there's good news. We'll celebrate with champagne later, but I just hope he won't disappoint us like Hollande did."
Many in the crowd acknowledged that Macron risks becoming a lame duck without a parliamentary majority and said they hoped French voters would back En Marche! in the legislative elections next month.
But the movement has no experience of fighting what will, in effect, be 577 micro-elections in each parliamentary constituency.
Mathieu Leveque, 19, is one of a dedicated army of young volunteers who campaigned for him and will now work for the parliamentary elections.
"This is a fantastic night. For weeks I've been getting up at 4am to put up posters," said Leveque, a business student. "We've put our hearts into combatting the Front National, its intolerance and insane economic policies."
Emmanuel Langlet, 40, a financial consultant, said: "I was attracted by Mr Macron's youth and his optimistic message. We weren't sure if Marine Le Pen was going to pull off a last-minute victory. Now I'm happy that this will give a good image of France in the world, but I know the job is only just beginning. I think French voters will be intelligent enough to give their new president a majority in the National Assembly."
France has taken a step into the political unknown. Macron is the first president from outside an established party in more than a century.
A former Rothschild banker, he served as Hollande's economy minister - in France ministers do not have to be elected - but lacks a parliamentary power base. Without a majority or the support of a reliable coalition, he may struggle to fulfil his promises to reform rigid labour laws, slash business taxes and cut the bloated public sector and public spending.
If En Marche! fails to win enough seats, he will be at the mercy of unwieldy parliamentary coalitions. His reforms may be blocked or watered down as he balances competing demands from allies on the left and right. Another challenge will be to reach out to La France Profonde, the "forgotten France" of small, impoverished towns and villages that have been left behind as industries die and farmers struggle to make ends meet.
If he fails, the populist wave led by the National Front will certainly surge again. "In many ways, this is the last throw of the dice, the last time someone from the middle ground will have a chance to fix problems like high unemployment," said Florence Galichet, 50, a webmaster. "I hope he'll manage it."
Macron will also have to pick a prime minister and cabinet. He has set himself the daunting task of bringing in figures from the left and the right, and from civil society, which is bound to entail tortuous negotiations. One stumbling block in Macron's efforts to woo senior political figures may be his insistence that they must leave their parties and run for the parliamentary elections under his banner. The candidates of the two mainstream parties, the Socialists and the centre-right Republicans, crashed out of the presidential race in the first round of voting. They are weakened and divided, but still hoping to use their political apparatus and networks of local support stage a comeback.
Macron has announced that he has picked his prime minister, but has not specified who it is. Xavier Bertrand, 52, president of the northern France region, is said to be his preferred choice, but is reportedly balking as his party, the Republicans, are fielding candidates in all constituencies for the parliamentary elections.
Another frontrunner is Franois Bayrou, the centrist leader of the MoDem (Democratic Movement) party and a former presidential candidate.
Macron has promised new legislation to clean up French politics after a campaign bogged down by sleaze. His pledge to bypass parliament and push through decrees within months to "simplify" France's restrictive labour code is likely to set him on collision course with unions and lead to street protests.
Le Pen's larger-than-expected defeat was a crushing reality check for the far-right forces who seek to overthrow Europe: Despite the victories for Brexit and Donald Trump in the US, they are likely to be shut out of power for years.
Western European voters have delivered mainstream candidates to office despite a post-November sense that an anti-immigrant populist wave was washing over the Western world. Far-right candidates in Austria, the Netherlands and France have faltered. The eurosceptic far-right party in Germany has collapsed in recent polls ahead of September elections. And an unforgiving election calendar now offers few routes into power for years.
The thwarted momentum comes despite clear evidence that views that would have been taboo to express just a few years ago are no longer too toxic to exclude politicians from coming a breath away from leadership.
When Le Pen's father reached a presidential runoff in 2002, his opponent refused even to debate with him. This time, many French citizens sat out the election altogether because they detested both Le Pen and Macron. Le Pen's result was still a historic high for her party.