On 18 August 1572, Paris hosted the lavish wedding of Marguerite de Valois and Henri de Navarre, which was designed to seal the reconciliation of France's Catholics and Protestants. Only six days later, the execution, on the orders of the king's council, of the Protestant leaders unleashed a vast massacre by Catholics of thousands of Protestants in Paris and elsewhere. How did the celebration of concord give way so quickly to an explosion of violence, and the preventitive execution of a few leaders to unrestrained carnage? Who were the key players in these terrible events? Arlette Jouanna...