October 11, 1521: Leo X conferred the title "Fidei Defensor" (Defender of the Faith) upon England's Henry VIII for his tract "The Assertion of the Seven Sacraments," written against Martin Luther. Three popes and 13 years later, Henry severed all ties with Rome, making the Church of England a separate church body (see issue 48: Thomas Cranmer).
October 11, 1531: Swiss reformer Ulrich Zwingli dies in the Battle of Kappel (see issue 4: Ulrich Zwingli).
October 11, 1551: The 13th Session of the Council of Trent opens to discuss the Eucharist. The Counter-Reformation Council affirmed the doctrine of transubstantiation and repudiated Lutheran, Calvinist, and Zwinglian eucharistic doctrines.