King Henry VIII of England was given the title 'Defender of the Faith' by Pope Leo X after he wrote a defense of the Seven Sacraments against the attacks of the Protestant Reformation. Despite this, Henry later established the Church of England, breaking away from the Catholic Church.
The answer to your question is that the title 'Defender of the Faith' was given to King Henry VIII of England for his work, 'Defense of the Seven Sacraments'. In this document, Henry VIII defended the traditional practices of the Catholic Church against the criticisms being leveled by Martin Luther and other members of the Protestant Reformation movement.
In recognition of Henry VIII's strong Step-by-step explanation and defense of Catholic doctrine, Pope Leo X awarded him the title 'Fidei Defensor', or 'Defender of the Faith', in 1521. However, it is interesting to note that despite receiving this title, Henry later broke with the Catholic Church to establish the Church of England.
Thus, the title 'Defender of the Faith' was awarded by the Pope to those who successfully and rigorously defended the principles and doctrines of the Catholic Church. In this specific case, it was King Henry VIII who was awarded this title for his defense of the seven sacraments.
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