"We cannot afford to lose this war. But for the past 10 years, left-wing and right-wing governments have done everything they can for us to lose it," Le Pen said days before the election, after a French citizen killed a police officer and wounded two more on the Champs-Elysees in an attack for which Isis asserted responsibility. "We need a presidency that acts and protects us," she said.
The violence played perfectly into the warnings of a woman who has been sounding the alarm for years that France's identity was slipping away to Muslims - even before a recent spate of terrorist attacks sent France into an official state of emergency.
Even Socialist President François Hollande briefly toyed with stripping dual citizens of their French nationality if they were convicted of terrorism charges, a signature Le Pen idea that critics said would relegate many French Muslims to second-class citizenship.
Born into a political family, the 48-year-old Le Pen was for decades among her father's closest confidantes as Jean-Marie Le Pen led his National Front party as an eccentric gathering of extremist politicians who thought that the Holocaust was just "a detail" of World War II. Over the decades, he became the living emblem of Europe's far-right politicians: cranky, offensive, tinged with the odor of being a Nazi sympathiser, but always far from power.
The daughter's political awakening came when she was 8, she has said, after the family's modest apartment was bombed and officials appeared to do little to find the culprit. The front of the building was blown off. No one died, but a baby survived only because a tree slowed its fall.
"We were not treated the same as others," she wrote in her 2006 autobiography, blaming official indifference on her father's political views.
But if her father was willing to give up ballot-box success in the name of ideological purity, Le Pen has proven a far more adept politician.
When Jean-Marie Le Pen slipped into the second round of the presidential election in 2002, there was little question that voters on both sides of the political spectrum would band together to defeat him. He captured less than 18 per cent of the vote, a crushing disappointment for a daughter who trained as a lawyer but spent the bulk of her career working inside the party.
This time, there is little expectation that voters will reject Le Pen simply because of the party's past association with Nazism.
After the 2002 loss, the younger Le Pen vowed to transform the movement into a force that could actually win elections.
She took over the party in 2011 and quickly moved to distance it from its roots. She said she was the best ally of France's Jews - because she would protect them against Muslim immigrants.
She made a bid for left-behind union members, the core of France's old left-wing alliance, by saying that she would protect their cherished social benefits by turning back the forces of globalisation.
And in a father-daughter drama worthy of Shakespeare, she expelled her father from the party after his views about the Holocaust became a distraction on the campaign trail. They say they no longer talk - although the elder Le Pen is still financing his daughter's bid.
Now she is a sizzling sparkplug on the campaign trail, firing up crowds who say none of the other contenders has anything fresh to say.
Before the first round, the mood at her rallies was in sharp contrast to her now-vanquished opponents, who sometimes seemed to struggle to indicate to crowds when they were supposed to cheer.
She has gathered supporters from across France's hard-hit north, where once-proud factories have been closed as jobs moved to Poland and China.
"My project is to give France its liberty back, to let it out of jail, to give you France back and to give France back to the world," Le Pen said to wild applause at her final Paris rally last week. "It is high time to set France free."
But if she wins, the France she would create could look radically different from the multicultural, plugged-into-Europe nation it is today.
Le Pen has vowed to erect border barriers and bar immigration both from inside and outside Europe. She says she would rebuild French manufacturing, which has struggled under competition from cheaper foreign goods, by seeking to bring back the French franc.
And she has listed a host of tactics she would use to make France less hospitable to its Muslim population, including the serving of pork in schools and the expulsion of any noncitizen who had been flagged for extra monitoring under France's anti-terror regime.
Critics say her tactics would range from unconstitutional to inhumane, and they warn that the financial panic unleashed by any attempt to leave the European Union would knock down her already-struggling supporters.
She says that the tide of history is on her side, pointing to the Brexit vote in the United Kingdom and the election of US President Donald Trump as signs that voters around the world are rejecting globalisation and immigration.
Trump's main failing so far, Le Pen said this month, is that he is turning into a conventional politician, and not upholding his more extreme campaign promises.
"He is in contradiction with the commitments he made," she told France Info radio. "I am coherent. I don't change my mind in a few days."
