military structure in Sweden, which did not bear immediate fruit in the Nordic Seven Years' War but was to have a lasting impact on Sweden's fortune. In 1544 he used the old Scandinavian concept of Uppbåd (levy or the prerogative to call up some fraction of men from each district in an emergency) to establish one of the first native standing armies in Europe. The men served on standby, remaining at home in peacetime, and being paid by tax concessions, but were required to assemble and drill. This system was later expanded as the Swedish allotment system. By 1560 when Gustav Vasa died, every ten peasants were required to provide one soldier who must serve anywhere domestic or foreign as required by the king. Casus belli After the deaths of Christian III and Gustav Vasa, in 1559 and 1560 respectively, both countries now had young and hawkish monarchs, Eric XIV of Sweden and Frederick II of Denmark. Frederick II envisioned the resurrection of the Kalmar Union under Danish leadership, while Eric wanted to finally break the dominating position of Denmark. Shortly after his coronation in 1559, King Frederick II of Denmark ordered his ageing field-commander Johan Rantzau to avenge the humiliating Danish defeat against the small peasant republic of Ditmarsh, which was defeated in a matter of a few weeks and brought under the Danish-Norwegian crown. During the next year, the Danish expansion continued with the possession of the Baltic Sea island of Ösel. In 1561, when a sizeable remnant of the Order states in the northern Baltics were secularized by its grand master Gotthard Kettler, both Denmark and Sweden were attracted to intervene in the Livonian War. During this conflict, King Eric of Sweden successfully obstructed the Danish plans to conquer Estonia. He sought to dominate the Baltic Sea, while unsuccessfully pressing for Frederick to remove the traditionally Swedish insignia of Three Crowns from the Danish coat of arms; a bone of contention since Christian III and Gustav Vasa. In February 1563, Swedish messengers were sent to Hesse to negotiate Eric's marriage with Christine of Hesse but were held back in Copenhagen. In retaliation, Eric added the insignia of Norway and Denmark to his own coat of arms and refused Danish requests to remove these symbols. Lübeck, upset over obstacles to trade introduced by Eric to hinder the Russian trade as well as withdrawn trade privileges, joined Denmark in