First Act of Supremacy 1534
The Act of Supremacy, 1534 (26 Hen. 8, c. 1) was the declaration by an Act of Parliament under King Henry VIII of England that he was 'the only supreme head in earth of the Church of England' and that the English crown shall enjoy "all honours, dignities, preeminences, jurisdictions, privileges, authorities, immunities, profits, and commodities to the said dignity".
Henry, who had been declared "Defender of the Faith" (Fidei Defensor) for his pamphlet accusing Martin Luther of heresy, was now confirmed as head of the Church of England. This made official the English Reformation that had been brewing since 1527, along with a rather long-lasting distrust between England and the Catholic Church. The act was a result of Henry's want of an annulment of his marriage to Catherine of Aragon; however, Pope Clement VII had refused to grant it. The Act of Supremacy caused any act of allegiance to the Pope (or any other non-Episcopalian religion, for that matter) to be considered treason. This act was repealed in 1554 by Henry's daughter, Queen Mary I, who was a staunch Catholic.
Second Act of Supremacy 1559
The second Act of Supremacy (1559) was the reinstatement of the original Act of Supremacy (1534). The English monarch was again the head of the Church of England, above the authority of the Pope. This was enacted by Queen Elizabeth I, the Protestant monarch after the Catholic Mary I. Anyone who took public or church office was forced to take the Oath of Supremacy; there were penalties for violating that oath. However, Elizabeth, who was a politique, did not prosecute Nonconformists, or those who did not follow the Church of England, unless their worship undermined the authority of the English monarch.
