<P> Later the same year, Victor Emmanuel II of Italy seized Rome from the pope's control and substantially completed the Italian unification . </P> <P> In 1929, the Lateran Treaty between the Kingdom of Italy and the Holy See established Vatican City as an independent city - state, guaranteeing papal independence from secular rule . </P> <P> In 1950, Pope Pius XII defined the Assumption of Mary as dogma, the only time that a pope has spoken ex cathedra since papal infallibility was explicitly declared . </P> <P> The Petrine Doctrine is still controversial as an issue of doctrine that continues to divide the eastern and western churches and separate Protestants from Rome . </P>

What major event challenged the universal power of the catholic church