Encouraged by the protection of such powerful patrons he preached freely and with great success in several districts of Scotland. The clansmen were so united to their lords that they were prepared to follow their example even in matters of religion. The bishops and the regent, to whom these proceedings must have been known, were strangely oblivious to their duties, and when at last they mustered up sufficient courage to summon Knox to appear at Edinburgh (1556), they were so alarmed by the strength of his following that they abandoned the trial. Knox, encouraged by their cowardice, preached openly in the capital, and even went so far as to address a letter to the regent calling upon her to open her mind for the reception of the truth.[13] By this public challenge, however, he overshot the mark, and not being gifted with any particular desire to suffer martyrdom for the faith, he left Scotland suddenly and retired to the Continent (1556). For years he was the leading spirit in many of the fierce and unseemly disputes between the English Protestant exiles in Geneva and Frankfurt. Although summoned more than once by his followers to return, he contented himself with sending them written exhortations to stand firm in the faith, or by publishing violent pamphlets such as /The First Blast of the Trumpet against the Monstrous Regiment of Women/, in which he undertook to prove that the rule of women is repugnant to nature, contrary to God's ordinances, and subversive of good order, equity, and justice. Though this document was aimed principally against Catharine de' Medici, Queen Mary of England, and Mary of Guise regent of Scotland, it rankled in the mind of Queen Elizabeth after her accession, and did not serve to raise the apostle of Scotland in her estimation.