Our friends at Refo500 remind us that it was on the night of August 23-24, 1572 that the horrific ‘St Bartholomew’s Day Massacre’ took place. Heinrich Bullinger composed his De Persecutionibus Ecclesiæ Christianæ in the aftermath of that horrific slaughter of over 100,000 Hugenots (‘Confederates’ – the name given to the Reformed in France who adhered to the reformation of Zwingli and Calvin).
The Catholics were overjoyed at the destruction of the Reformed in Paris. As Schaff notes-
The horrible massacre of St. Bartholomew (Aug. 24, 1572) was sanctioned by Pope Gregory XIII., who celebrated it by public thanksgivings, and with a medal bearing his image, an avenging angel and the inscription, Ugonottorum strages