Complex sentence: During the Tudor conquest of Ireland by the Protestant state of England in the course of the 16th century, the Elizabethan state failed to convert the Catholic natives to Protestantism and there was also a vigorous campaign of proselytizing by Counter Reformation Catholic clergy.
Split into simpler sentences: During the Tudor conquest of Ireland by the Protestant state of England in the course of the 16th century, the Elizabethan state failed to convert the population to Protestantism. There was also a vigorous campaign of proselytizing by Counter Reformation Catholic clergy.