Popish Plot
Popish Plot (1678):
The Popish Plot was a supposed conspiracy by Roman Catholics to kill the Protestant Charles II of England and replace him as king by his Roman Catholic brother, James, Duke of York.
Principal item of the plot was a manuscript written by Titus Oates and Israel Tonge that pretended the Roman Catholic Church to approve the assassination of Charles II by English Jesuits. The alleged plot resulted in an anti-Catholic frenzy, in which 24 Catholics were executed for treason and serveral others died in prison. The eventual discovery of the plot preceded the Exclusion Bill Crisis.
Sources:
http://dspace.dial.pipex.com/town/parade/abj76/PG/pieces/popish_plot.shtml