France, Nov. 13 -- The day began in Paris with a security exercise. "In the morning, an exercise [had been] organised involving the security forces, in case of a mass killing in Paris," recalls Cazeneuve of 13 November 2015.

In the afternoon, he presented a national plan to combat arms trafficking at the Hauts-de-Seine prefecture, north-west of Paris. In the early evening, he decorated the civil servants who had assisted police officer Clarissa Jean-Philippe during the January 2015 terror attacks.

In short, for Cazeneuve: "This was a day entirely devoted to preventing and combatting terrorism."

France marks decade of 2015 Paris attacks The call from Hollande

At 8pm, everything changed.

"I received a call from the president of the rep...