 Claude attended the wedding between Henry of Navarre and her sister Margaret of Valois in Paris in August 1572.On her way there, she had been ill and cared for by her mother in Chalons, which was the reason why Catherine de Medici had been absent from the royal court during the border attack of Jean de Genlis near the Spanish Netherlands in July, which was used by Admiral Coligny to attempt to convince Charles IX to declare war on Spain.On evening of the Massacre, Claude was evidently informed that a massacre was to take place against the groom of her sister and his followers, and Margaret of Valois described how Claude had tears in her eyes and tried to stop her from leaving their mother's chamber, when Margaret was about to retire to the chamber of her spouse.