But catastrophe struck in 1559.  The gallant and athletic Henri was killed by accident in a friendly joust with his faithful companion Montgomery.  The lance, designed merely to throw the competitor from the horse, broke and the splintered end ran through Henri's head.  He suffered terribly for days and then died.  Catherine had just married her oldest son to the Scottish princess Mary Stuart (Mary Queen of Scots).  The new king was only 16 years old.  Word got out that the Protestants were planning to take advantage of the weakened throne, and perhaps even to kidnap the sickly boy-king.  A meeting was arranged near here, and the Protestants fell to a Catholic ambush.  They were brought here for judgment and execution.  Some were hanged, some beheaded, some thrown into the river below.  As a warning to others, the castle was decorated with heads and rotting corpses.  Legend has it that Catherine de Médicis, François II, and Mary Stewart set their table among the cadavers in celebration of the Catholic victory.