In March 1179, Alexander III held the Third Council of the Lateran, one of the most important mediaeval church councils, reckoned by the Catholic Church as the eleventh ecumenical council. Its acts embodied several of the Pope's proposals for the betterment of the condition of the Church, among them the law requiring that no one could be elected pope without the votes of two-thirds of the cardinals. The rule was altered slightly in 1996, but was restored in 2007. The period from 1177, which saw the submission of both emperor Frederick and anti-pope Calixtus III, and this synod/council marked the summit of Alexander III's power.