The Saint Bartholomew's Day massacre, occurring in 1572, was a series of targeted killings and widespread mob violence against Huguenots, French Calvinist Protestants, during the French Wars of Religion. This period of intense conflict is believed to have been initiated by Queen Catherine de' Medici and targeted prominent Huguenots who had gathered in Paris for the wedding of King Charles IX's sister, Margaret, to the Protestant King Henry III of Navarre. The violence began on the night of August 23-24, following the attempted assassination of Admiral Gaspard de Coligny, a key Huguenot leader. The killings, which initially targeted Huguenot leaders in Paris, soon spread throughout the city and into the countryside, resulting in an estimated 5,000 to 30,000 deaths across France.

The massacre represented a significant turning point in the religious wars, severely weakening the Huguenot political movement and leading many to convert or become more radicalized. The event had a profound impact across Europe, reinforcing for Protestants the perception of Catholicism as a violent and untrustworthy faith. The context leading up to the massacre involved precarious peace treaties, the controversial marriage uniting Catholic and Protestant factions, and rising tensions within Paris due to economic hardship and anti-Huguenot sentiment, further exacerbated by the attempted assassination of Admiral Coligny.

The events leading to the Saint Bartholomew's Day massacre were a complex interplay of political maneuvering and religious animosity. A fragile peace, established in 1570 after a period of civil war, was undermined by hardline Catholics who opposed any concessions to Protestants. The Huguenot leader, Admiral Gaspard de Coligny, had been readmitted to the King's council, alarming staunch Catholics. Queen Mother Catherine de' Medici, seeking stability and mindful of the kingdom's financial state and the Huguenots' fortified towns, supported the peace and Coligny's reintegration. To solidify this peace, a marriage was arranged between her daughter, Margaret, and the Protestant Henry of Navarre, a union that faced opposition from traditionalist Catholics and even condemnation from the Pope and King Philip II of Spain.

The royal wedding, intended to unite warring factions, instead concentrated a large number of Huguenots in Paris, a city with a deeply anti-Protestant populace. Encouraged by Catholic preachers, Parisians viewed the marriage of a French princess to a Protestant with horror, increasing political tensions. Economic hardship, including poor harvests and rising taxes, further inflamed the common people, who were also resentful of the ostentatious displays during the wedding. Tensions were amplified by the removal of a controversial open-air cross erected on the site of a executed Huguenot's home, an event that had previously led to riots and deaths. The court itself was divided, with significant hesitation from French clergy regarding the irregular marriage, and rivalries between powerful families like the Guises and Montmorencys resurfaced, contributing to the volatile atmosphere.

The situation reached a critical point with the attempted assassination of Admiral Coligny on August 22, 1572, just days after the royal wedding. Seriously wounded, Coligny was a highly respected Huguenot leader, and the attack heightened fears of Protestant retaliation. While the King promised to punish the perpetrators, the Queen Mother and her advisors, concerned about potential Huguenot reprisals and influenced by figures like Albert de Gondi, reportedly made the decision to eliminate key Protestant leaders. This decision, made on the eve of the Feast of Saint Bartholomew the Apostle, led to the summoning of Parisian municipal authorities. They were instructed to secure the city, and the King's Swiss mercenaries were tasked with carrying out the executions of a designated list of Protestant nobles.