The Lutheran form of Protestantism entered France about 1520 and soon met with opposition from the Catholics.
The work of John Calvin (1509-1564) greatly influenced and furthered the cause of French Protestantism which secured adherents chiefly from the middle class and the nobility.
As the Protestant movement gained in strength, opposition to it likewise increased until, toward the end of the reign of Francis I (1497-1547), the Huguenots were being severely persecuted. The Protestants developed their organization as they increased in numbers, holding their first synod in 1559, at which time they adopted a code based on the doctrines of Calvinism.
Persecution of the Huguenots as heretics increased under Henry II, who reigned from 1547 to 1559.
The members of the Guise family, which had grown in power during the reign of Francis I, were bitterly opposed to the Huguenots, whose cause was upheld by the powerful and influential Bourbons. Friction between the opposing factions increased until the first \civil war broke out in 1562, when the Guises seized the young king, Charles IX (1550-1574) and the Huguenots, under Prince de Conde and Admiral Colginy, took up arms against the Catholics.
A series of eight civil wars followed which lasted with intervals of peace, until the treaty of Vervins (q1598) brought the conflicts to an end. Queen-mother and regent for Cahrles IX, in her efforts to maintain herself in power, sometimes opposed and sometimes favored the cause of the Huguenots, depending upon what she considered at the time to be politically advantageous.
On August 24, 1572, thousands of Protestants were killed in the Massacre of St. Bartholomew, but this only served to strengthen the cause of the Huguenots. King Henry IV (1552-1610), whom the Protestants had supported for the throne, signed the Edict of Nantes (1598), which guaranteed the Huguenots religious and civil liberty."