Three Leagues
As the Catholic cantons refused to help the Three Leagues ("Drei Bünde") in the Grisons during the Musso war against the Duchy of Milan, Zürich promptly considered this a breach of contracts between the confederacy and the Three Leagues and declared an embargo against the five alpine Catholic cantons, in which Bern also participated. While the "Tagsatzung" had successfully mediated in 1529, on this occasion the attempt failed, not least because Huldrych Zwingli, the Protestant leader, was eager for a military confrontation. Pressed by the food embargo, the Catholic cantons declared war on Zürich on 9 October 1531.