Battle of Wolgast
Christian IV of Denmark, encouraged by his successes at Stralsund, assembled another army off the German coast on the Island of Usedom.
This landed at the mouth of the Oder and progressed as far as Wolgast, taking the place on 3 August, 1628. There it was met by Wallenstein's forces, and, on 12 August, 1628, Christian was once again defeated and driven back to the sea. This was the final straw for Christian, who sued for peace.
The growing ascendancy of the Catholics in North Germany in and after 1623 almost induced Christian, for purely political reasons, to intervene directly in the Thirty Years' War. For a time, however, he stayed his hand, but the urgent solicitations of the western powers, and, above all, his fear lest Gustavus Adolphus should supplant him as the champion of the Protestant cause, finally led him to plunge into war against the combined forces of the emperor and the League, without any adequate guarantees of co-operation from abroad. On May 9, 1625 Christian quit Denmark for the front. He had at his disposal from 19,000 to 25,000 men, and at first gained some successes; but on August 27, 1626 he was utterly routed by Tilly at Lutter-am-Barenberge, and in the summer of 1627 both Tilly and Wallenstein, ravaging and burning, occupied the duchies and the whole peninsula of Jutland. In his extremity Christian now formed an alliance with Sweden (January 1, 1628), whereby Gustavus Adolphus pledged himself to assist Denmark with a fleet in case of need, and shortly afterwards a Swedo-Danish army and fleet compelled Wallenstein to raise the siege of Stralsund. Thus the possession of a superior sea-power enabled Denmark to tide over her worst difficulties, and in May 1629 Christian was able to conclude peace with the emperor at Lübeck, without any diminution of territory.