That’s the day that the Five Forest Cantons (Catholic all) declared war on Zurich and the Zwinglians. A few days before, Zwingli had written
“Be firm and do not fear war. For that peace which some are so urgently pressing upon us is not peace but war. And the war for which I am so insistent is peace, not war; for I do not thirst for the blood of anyone, nor will I drink it even in case of tumult. This is the end I have in view—the enervation of the oligarchy. Unless this takes place neither the truth of the Gospel nor its ministers will be safe among us. I have in mind nothing cruel, but what I do is friendly and paternal. I desire to save some who are perishing through ignorance. I am labouring to preserve liberty. Fear nothing; for we shall so manage all things with the goodness and the alliance of God that you shall not be ashamed nor displeased because of us.”
… marched thirty thousand strong to Cappel, a border town ten miles directly south of Zurich. Zwingli accompanied the troops as chaplain, as his office obligated him to do. He went on horseback, carrying “on his shoulder a beautiful halberd.” It was his plan to strike a quick and crushing blow upon the disorganised Five Cantons, and then extort from them the abrogation of the Austrian alliance, the renunciation of foreign pensions, and full liberty to preach the Reformed doctrines within their borders. It was to see that these things were insisted on that he accompanied the host. But as they were directly opposite to the Five Cantons’ ideas and could only be obtained by bloodshed, he was held by them to be their deadliest foe; and the Zurich authorities, knowing that he was considered by them as the cause of the whole trouble, had endeavoured to keep him in Zurich and even appointed another to be chaplain.
But the first Cappel war was over as soon as it was begun. On June 10th the allies received a moving appeal from the chief magistrate of Glarus to await a proposition from the Five Cantons. Zwingli perceived the folly of treating with them and patching up a peace which secured none of the objects of the threatened war. He said to the bearer of the appeal: “You will have to give an account to God for this. While the enemy is weak and without arms, he speaks fair: you believe him and make peace. But when he is fully armed, he will not spare us, and then no peace will he make with us.” The man replied: “I trust in God that all will turn out well. Let us act always for the best.”
On June 11th, Zwingli wrote from the field to the Small and Great Councils of Zurich a long letter, in which he gave his idea of the necessary conditions for a lasting peace: I. The Forest Cantons must allow the Word of God to be freely preached among them. II. Pensions were to be for ever foresworn. III. Distribution of such pensions was to be punished corporally and by fine. IV. The Forest Cantons were to pay indemnity to Zurich and Bern.
Zurich and the Forest Cantons made peace but Zwingli was right. Within two years they waged war against Zurich again, and killed Zwingli at the same spot at Kappel, on 11 October, 1531.