Just days before Easter 2018, Redouane Lakdim, a 25-year-old Moroccan criminal, opened fire on passengers in a car in southern France, killing one. Minutes later he fired on a group of police officers who were jogging near the castle in Carcassonne. He then drove to the town of Trèbes and stormed a supermarket, shooting dead the shop’s butcher and a customer, a retired bricklayer, whilst screaming ‘Allahu akbar’. Police arrived shortly after the start of the siege, managing to get some people out. But the attacker kept one woman hostage. It was then that Arnaud Beltrame, a 44 year old lieutenant-colonel in the gendarmerie, offered...