Huldrych Zwingli was a leading figure of the Protestant Reformation in Switzerland. He studied theology and became a priest, growing disillusioned with the Catholic Church. In 1519, he became a preacher in Zurich and began preaching reforms based solely on scripture. By 1523, Zurich had officially adopted Protestant theology. Zwingli believed in simplicity in worship, opposed Catholic doctrines like transubstantiation, and favored a state-run church. However, he disagreed with Luther on the real presence in communion. Zwingli was killed in battle in 1531 while fighting in defense of the Reformation in Switzerland.