"...The Popes also, by whom Elizabeth was justly regarded as the great prop of the Reformed religion, endeavoured to excite against her such of her subjects as still owned obedience to the See of Rome. At length, in 1570—71, Pius II., then the reigning Pope, published a bull, or sentence of excommunication, by which he deprived Queen Elizabeth (as far as his sentence could) of her hopes of heaven, and of her kingdom upon earth, excluded her from the privileges of Christians, and delivered her over as a criminal to whomsoever should step forth to vindicate the Church, by putting to death its greatest enemy. The zeal of the English Catholics was kindled by this sentence from the Head of their Church..."
As Walter Scott relates to his grandson, "Hugh Littlejohn" (Tales of a Grandfather), Pope Pius V excommunicated Elizabeth I, believing that Mary, Queen of Scots, a Catholic was the rightful sovereign. The excommunication occurred on February 25, 1570.