Complex sentence: It entered English political discourse during the Exclusion Bill crisis of 1678--1681 and applied to those opposed to the hereditary ascendance of the Catholic Duke of York, future James II, to the throne.
Split into simpler sentences: It entered English political discourse during the Exclusion Bill crisis of 1678--1681. The term was then used during the Exclusion Bill crisis and applied to those opposed to the hereditary ascendance of the Catholic Duke of York, future James II, to the throne.