Antipope Felix V
The institution of a cardinal protector of a nation-state may have originated in the 14th century, serving as a predecessor for the diplomatic institutions of the Holy See developed in the 16th century. The institution of the crown-cardinal first became a dominant one within the College of Cardinals with the consistory of Pope Eugene IV on December 18, 1439 (on the heels of the election of Antipope Felix V by the Council of Basel), which nominated an unprecedented number of cardinals with strong ties to European monarchs and other political institutions.