In 1519, Zwingli became the pastor of the Grossmünster in Zürich where he began to preach ideas on reforming the Catholic Church. In his first public controversy in 1522, he attacked the custom of fasting during Lent. In his publications, he noted corruption in the ecclesiastical hierarchy, promoted clerical marriage, and attacked the use of images in places of worship. In 1525, Zwingli introduced a new communion liturgy to replace the mass. Zwingli also clashed with the radical wing of the Reformation, the Anabaptists, which resulted in their persecution.
The Reformation spread to other parts of the Swiss Confederation, but several cantons resisted, preferring to remain Catholic. Zwingli formed an alliance of Reformed cantons which divided the Confederation along religious lines. In 1529, a war between the two sides was averted at the last moment. Meanwhile, Zwingli's ideas came to the attention of Martin Luther and other reformers. They met at the Marburg Colloquy and although they agreed on many points of doctrine, they could not reach an accord on the doctrine of the presence of Christ in the Eucharist.
In 1531 Zwingli's alliance applied an unsuccessful food blockade on the Catholic cantons. The cantons responded with an attack at a moment when Zürich was badly prepared. Zwingli was killed in battle at the age of 47. His legacy lives on in the confessions, liturgy, and church orders of the Reformed churches of today.