Regnans in Excelsis (1570)

Today in 1570 marks the issuance of the papal bull Regnans in Excelsis by Pope St. Pius V. Pius believed in the supreme authority of the papacy over secular rulers, so he excommunicated and deposed England’s Queen Elizabeth I. He also went on to release English Catholics from their allegiance to Elizabeth. This only made things worse for them, and led to increased persecutions. For most of the next three hundred years English Catholics were essentially driven underground. (Trivia: as a former Dominican, it was Pius who made it a practice for pontiffs to wear the white cassock.)