Former French president Francois Hollande maintained Sunday that jihadists had failed to divide the population with terror attacks in January 2015 that killed 17 people.
On Wednesday, 14 people face trial in connection with the murders, which heralded an unprecedented wave of attacks in France.
They are accused of helping to prepare the killings, but three who disappeared in northern Syria and Iraq will be tried in absentia.
"I feared the society could tear itself apart, because that was the terrorists' goal: divide the French, stigmatise Muslims, create the spirit of hatred that in the end is what motivates them," Hollande told France 2 television.
From January 7-9, 2015, gunmen attacked the satirical newspaper Charlie Hebdo in Paris, killed policewoman Clarissa Jean-Philippe in a southern suburb and attacked a Jewish supermarket just east of the capital.
Twelve people died during the newspaper attack, and four were killed in the supermarket.
Police identified three gunmen, all of whom died in shootouts, and said they had coordinated their violence for the Islamic State group.
Hollande, who was president at the time, said they "failed" in their bid to stoke religious or racial hatred because the population's reaction "was remarkable".
A demonstration held on January 11 to denounce terror acts was attended by more than four million people, according to estimates.
The country nonetheless suffered subsequent attacks, notably on November 13, 2015 when 130 people died and hundreds more were wounded in coordinated attacks by Islamic extremists.
It has also been rocked by social unrest that included a wave of violent protests by "yellow vest" militants who say current President Emmanuel Macron ignores the needs of ordinary citizens.