President Francois Hollande leads ceremonies on Friday to mark 70 years since the Allied invasion of southern France which, two months after D-Day, pushed the exhausted Nazi army back towards Germany and hastened the end of World War II in Europe.
Joining Hollande will be 15 leaders from France's former African colonies, in recognition of the key role troops from these countries played in liberating France from the scourge of Adolf Hitler's Nazis.
They and representatives of the other 13 countries that took part in the landings will attend an international ceremony on board the French aircraft carrier Charles de Gaulle, anchored off the southern city of Toulon.
After the success of the Normandy beach landings, the Allies needed to open up a second front in France to squeeze the demoralised German army and retake the ports of Marseille and Toulon to resupply forces pouring into the hole smashed into the line on D-Day.
The result was "Operation Dragoon", launched on the beaches near Marseille on August 15, 1944, with a total force of 450,000 men.
In contrast to the Normandy landings, where there was only a token French army presence, more than half (250,000) of the invading force was French.
In turn, this French force had a large number of troops from France's then colonies, mainly from Algeria and Morocco, but also infantry from Senegal and soldiers from Pacific islands.
The invasion "succeeded much more quickly than expected", historian Jean-Marie Guillon told AFP.
The operation was "inextricably linked" to the better-known Normandy landings on June 6, he said.
"They were supposed to happen at the same time. It was only in April 1944 that they were separated, for practical reasons: there weren't enough boats."
Facing the Allies was the German 19th army with 250,000 badly equipped and shattered troops spread all along the coast, poorly defended with barbed wire, mines and heavy artillery.
As a result of this mismatch, the bloodshed seen on the Normandy beaches was largely avoided as the Germans quickly realised they could not defend their position.
On the evening of August 15, of the 100,000 men who had successfully landed, around 1,000 had fallen, death on a much smaller scale than D-Day, which saw some 10,000 casualties.
"We underestimate the importance of these landings," said Guillon, adding that they were less well-known than the D-Day invasion because "they went too well!"
- Hitler's 'saddest day' -
The Germans retreated rapidly, chased into the mountains by the rampant Allies, who were able to establish a supply base for the later invasion of Germany itself.
Hitler described it as "the saddest day of his life", and it led 10 days later to the joyful liberation of Paris.
Unlike ceremonies held in Normandy to mark the 70th anniversary of D-Day on June 6 -- attended by a phalanx of world leaders including US President Barack Obama and Queen Elizabeth II -- Friday's events promise to be more low key.
Organisers expect some 240 veterans to mark the occasion, including around 40 from the former colonies. Four Algerian veterans will receive the Legion d'Honneur, France's highest honour.
On Friday morning, Hollande will pay tribute in Toulon to the Allied forces, Free French troops, soldiers from the African army and Resistance fighters who died to liberate France.
Later, the international dignitaries will join the French leader for the ceremony on the Charles de Gaulle.
The international meeting on D-Day, which took place at the height of the Ukraine crisis, gave rise to a flurry of diplomacy and saw the first meeting between Russian President Vladimir Putin and Ukrainian counterpart Petro Poroshenko.