Foreign allies provided Supply financing and other assistance Assistance to both sides , with Habsburg Spain and the Duchy of Savoy supporting Supporting the Guises , and England supporting Supporting the Protestant side led by the Condés and by the Protestant Jeanne d'Albret , wife of Antoine de Bourbon , King of Navarre , and her son , Henry of Navarre .

Catherine , however , later hardened Cause_change_of_strength her stance and , at the time of the St. Bartholomew 's Day massacre in 1572 , sided with the Guises .