After the separation of the Eastern and Western churches in 1054, the holding of councils by the pope became a way to give guidance to the church, both locally and ecumenically (for the entire church), on varying ecclesiastical matters. One of the most significant of these was the Council of Trent, held in the mid-1500s, which considered such weighty matters as the Lutheran Protestant Reformation and how to counter it, disciplinary reforms in the church, the definition of dogma, and ways to establish key tenets of Roman Catholicism. In fact, the growing complexities of the issues at stake grew so voluminous that it took 18 years, spanning the reigns of five popes, for the Council of Trent to actually convene.