One of the most important popes of the 9th century, Nicholas I was a strong defender of papal authority. His papacy focused on centralizing power in Rome, addressing clerical abuses, and asserting the papacy's supremacy in both religious and political matters. Nationality: Papal States Born: January 1, 0820 Died: November 17, 0867 Pontificate: May 2, 0858 – November 13, 0867