PARIS — The aftermath of terrorist attacks in France has taken on a grim familiarity: political recriminations; the prosecutor of terrorism cases on the nightly news; the family photographs of the victims, their lives cut short.

In the wake of Friday’s attack in the small southern town of Trèbes, what altered this violent narrative were the extraordinary actions of an individual whose heroism gave people a way to come together, and its culmination in a supermarket, an ordinary place familiar to every Frenchman and woman — rural or urban, Christian or Muslim, young or old — so that everyone was able to imagine being there.

The hero was Lt. Col. Arnaud Beltrame of the French Gendarmerie who volunteered to exchange places with a hostage — a cashier — and was killed. He will be honored Wednesday in a ceremony at Les Invalides in Paris and eulogized by President Emmanuel Macron.

“One tries to understand it, but one cannot get there,” said Patricia Perderiset, 65, a retiree who had been shopping in the Trèbes market, the Super U, for Easter eggs for her grandchildren.