The Wars of Religion
In reaction to the dominating power at court of the Catholic Guises, La Renaudie, a Protestant gentleman of Périgord, perhaps with the indirect encouragement of Louis of Bourbon, Prince of Condé, organised a palace coup, the conspiracy of Amboise, to seize the person of the Duke of Guise and his brother Charles, the Cardinal of Lorraine. When the ill-organised plot was put off for six days, it was discovered by the court well ahead of time. On 12 March 1560, the Huguenots stormed the Château d'Amboise, to which the Guises had moved the young king and queen for safety. The uprising was violently suppressed, with 1,200 executed, many within sight of the castle. In the immediate aftermath Condé was obliged to flee the court, and the power of the Guises was supreme. The discourse which Coligny, leader of the Huguenots, pronounced against les Guises in the Assembly of Notables at Fontainebleau (August 1560), did not influence King Francis II in the least, but resulted rather in the imprisonment of Condé, at Charles's behest.
However, the king died on 5 December 1560, making Mary, Queen of Scots a widow, and of little political importance in France. The Guises lost status alongside her, thus making a year full of calamity for the Guises both in Scotland and France. Within a year and a half, their influence waxed great and waned. After the accession of Charles IX, the Duke of Guise lived in retirement on his estates.
The regent, Catherine de' Medici, was at first inclined to favour the Protestants. To defend the Catholic cause, the Duke of Guise, together with his old enemy, the Constable de Montmorency and the Maréchal de Saint-André formed the so-called triumvirate opposed to the policy of concessions which Catherine de' Medici attempted to inaugurate in favour of the Protestants. His former military hero's public image was changing: "he could not serve for long as the military executive of this extreme political, ultra-montane, pro-Spanish junta without attracting his share of odium," N. M. Sutherland has observed in describing the lead-up to his assassination.
The plan of the Triumvirate was to treat with Habsburg Spain and the Holy See, and also to come to an understanding with the Lutheran princes of Germany to induce them to abandon the idea of covertly backing the French Protestants. About July 1561, Guise wrote to this effect to the Duke of Württemberg. The Colloquy at Poissy (September and October 1561) between theologians of the two confessions was fruitless, and the conciliation policy of Catherine de' Medici was defeated. From 15 to 18 February 1562, Guise visited the Duke of Württemberg at Saverne, and convinced him that if the conference at Poissy had failed, the fault was that of the Calvinists.
As Guise passed through Wassy-sur-Blaise on his way to Paris (1 March 1562), a massacre of Protestants took place. It is not known to what extent he was responsible for this, but the Massacre of Vassy kindled open military conflict in the French Wars of Religion. The siege of Bourges in September was the opening episode, then Rouen was retaken from the Protestants by Guise after a month's siege (October); the Battle of Dreux (19 December), at which Montmorency was taken prisoner and Saint-André slain, was in the end turned by Guise to the advantage of the Catholic cause, and Condé, leader of the Huguenots, was taken prisoner.