First Polish War
The first Polish war, or the Polish–Swedish War 1563—1568, was an armed conflict between the Kingdom of Poland and the Grand Duchy of Lithuania and the Kingdom of Sweden between the years 1563 and 1568. The conflict began after the Kingdom of Denmark and the Polish–Lithuanian Union created a confederation on the 5th of October 1563 and Poland–Lithuania joined the Danish side in the Nordic Seven Years' War. Poland never proclaimed an official declaration of war. Several minor ceasefires were signed during the war. No formal peace was ever announced, but the war ended  with John III's accession to the Swedish throne. The war. In August 1563, the Nordic Seven Years' War broke out after Denmark and Lübeck declared war on Sweden. Sweden attacked the Danish possessions in Estonia. After the conclusion of the Danish-Polish covenant, a Polish force attacked the Swedes outside Lode, close to Koluvere. Eric XIV failed to arrange a standstill. At the beginning of 1565, the order Knight Kaspar von Oldenbokum set up a mercenary-army denominated the courtiers, who wanted to drive the Swedes out of Estonia to create a new order-empire under Poland. At the  end of April, they attacked the Swedish Fort Pernau and killed the entire Swedish establishment of one hundred men. On the 9th of June, the Pernau fortress surrendered, creating conditions for Polish ravages in the country. At the same time, the Poles attacked Karkus, but the Swedes managed to repel the attacks. The courtiers marched towards Reval and camped at Obermühlenberg. The Battle of Obermühlenberg began with the Swedes attacking, forcing the courtiers to retreat and pursuing them. During the battle, von Oldenbokum was mortally wounded, as a result of which the courtiers ceased to exist. In December, the Swedes  laid siege to Pernau. In March 1566, a Polish force came to the rescue of Pernau and Horn's troops marched to Ösel. The island was lay waste to, and the town of Arensburg was sacked. The Swedes again turned to Estonia, wreaked havoc to the Diocese of Riga and tried to recapture Pernau, which failed. At the beginning of 1567, the Poles avenged the Swedish devastation in the Riga diocese and attacked Swedish territory. On the 3rd of February, the Swedes suffered a major defeat at Runafer, losing about 2000 men. Horn was forced to resign as commander and  was replaced by Klas Kursell. In 1568, the Swedish troops got reinforcements and landed on Ösel anew where the Danish commander of Sonnenburg surrendered. A standstill with the rulers at Ösel was concluded. The courtiers attacked from Pernau into Swedish territory and the Swedes suffered defeat, which meant that a standstill was concluded. After Eric XIV was deposed in the autumn of 1568, the fighting with the union ceased.