
Foreign allies provided financing and other assistance to both sides, with Habsburg Spain and the Duchy of Savoy supporting the Guises, and England supporting the Protestant side led by the Condés and by the Protestant Jeanne d'Albret, Queen of Navarre and wife of Antoine de Bourbon, Duke of Vendôme and King of Navarre, and their son, Henry of Navarre. It also involved a dynastic power struggle between powerful noble families in the line for succession to the French throne: the wealthy, ambitious, and fervently Catholic ducal House of Guise (a cadet branch of the House of Lorraine, who claimed descent from Charlemagne) and their ally Anne de Montmorency, Constable of France (i.e., commander in chief of the French armed forces) versus the less wealthy House of Condé (a branch of the House of Bourbon), princes of the blood in the line of succession to the throne who were sympathetic to Calvinism. Much of the conflict took place during the long regency of Queen Catherine de' Medici, widow of Henry II of France, for her minor sons. It is estimated that three million people perished in this period from violence, famine, or disease in what is considered the second deadliest religious war in European history (surpassed only by the Thirty Years' War, which took eight million lives).

The French Wars of Religion were a prolonged period of war and popular unrest between Catholics and Huguenots ( Reformed/Calvinist Protestants) in the Kingdom of France between 15.

War of the Three Henrys (1587–89) Coutras Vimory Day of the Barricades Bartholomew Sommières Sancerre La Rochelle 1574–76 Dormans Edict of Beaulieu 1576–77 Treaty of Bergerac 1579–80 Treaty of Fleix 1585 Treaty of Nemours

1st–7th wars 1562–63 Edict of Saint-Germain Vassy Rouen Toulouse Vergt Dreux Orléans Edict of Amboise 1567–68 Saint-Denis Chartres 1568–70 Jarnac La Roche-l'Abeille Poitiers Orthez Moncontour 1572–73 Mons St.
