French Wars of Religion
Rise in factionalism

The crown continued efforts to remain neutral in the religious debate until the Affair of the Placards in October 1534, when Protestant radicals put up posters in Paris and other provincial towns that rejected the Catholic doctrine of the " Real presence of Christ in the Eucharist ". This allowed Protestantism to be clearly defined as heresy, while Francis was furious at the breach of security which had allowed one of the posters to be placed on the door of his bedchamber. Having been severely criticised for his initial tolerance, he was now encouraged to punish those responsible. On 21 February 1535, a number of those implicated in the Affair were executed in front of Notre-Dame de Paris, an event attended by Francis and members of the Ottoman embassy to France.

The fight against heresy intensified in the 1540s, forcing Protestants to worship in secret. In October 1545, Francis ordered the punishment of Waldensians based in the south-eastern village of Mérindol. A long-standing Proto-Protestantism tradition dating back to the 13th century, the Waldensians had recently affiliated with the Reformed church and became increasingly militant in their activities. In what became known as the Massacre of Mérindol, Provençal troops killed numerous residents and destroyed another 22 to 28 nearby villages, while hundreds of men were forced to become Galley slaves.

Francis I died on 31 March 1547 and was succeeded by his son Henry II, who continued the religious repression pursued by his father in the last years of his reign. His policies were even more severe since he sincerely believed all Protestants were heretics; on 27 June 1551, the Edict of Châteaubriant sharply curtailed their right to worship. Prohibitions were placed upon the distribution of 'heretical' literature, with the property of 'heretics' seizable by the crown.

From his base in Geneva, Calvin provided leadership and organisational structures for the Reformed Church of France. Calvinism proved attractive to people from across the social hierarchy and occupational divides and was highly regionalised, with no coherent pattern of geographical spread. Despite persecution, their numbers and power increased markedly, driven by the conversion to Calvinism of large sections of the nobility. Historians estimate that by the outbreak of war in 1562, there were around two million French Calvinists, including more than half of the nobility, backed by 1,200–1,250 churches. This constituted a substantial threat to the monarchy.
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