France more than any other European country felt the political effects of the Reformation. From the end of the Hundred Years War in 1450 until the mid-1500s, the royal Valois family had established its capital in Paris and gained a great deal of power over nobles, consolidating formerly sovereign regions into the French Kingdom.
The Valois were resolutely Catholic, all the more so because the pope had in 1515 granted the French king the authority to choose the bishops within his kingdom. Nevertheless, Calvinism spread quickly in France in the 1550s. Known as Huguenots, French Calvinists by 1560 numbered 2150 congregations to which some 10% of population belonged. This included over 40% of the nobility, and much of the population in many of the largest cities.
Huguenots called for a "Peace of Augsburg" - type arrangement of religious toleration in France: whereby regional assemblies would decide the religion of that region. Because this offered the possibility of compromise, the king and his powerful queen considered this idea. In response, an ultra-Catholic movement of nobles and clergy organized an army, known as the Holy League, to resist what they feared would be an attempt by the Huguenots to take over.