[6][4] Around 1560, after the collapse of the Livonian Order from their defeat at the Battle of Ērģeme, its old territories were divided between Sweden, Denmark, Russia, and Poland.

[7] The Russians managed to conquer large areas of Estonia in 1558, including Narva, which allegedly began the power vacuum that lasted for more than thirty years.

Dorpat, Wesenberg, and Fellin would also quickly fall into Russian rule with the rest of the Livonian Order's territory becoming Polish.

[citation needed] Denmark had a tough time stopping the Swedish defection, and the end of the Kalmar Union led to strong feelings of mistrust and hate between Swedes and Danes.

Eric XIV ordered him to provoke the Danes near Gotland or Bornholm and get them to attack the Swedish fleet, so that war on Denmark could be declared on the pretext of self-defense.

King Frederick had previously given out an order saying that the Danish navy was to patrol the Baltic Sea and visit all Swedish ships that were encountered.

[11] According to Danish sources, the Danes fired three blanks to warn the Swedes of their presence and to allow the crew onboard to show their good will.

[11][13][14] Almost immediately, a Swedish cannonball hit the mainmast of the Herkules, which fell down and landed in the middle of the firing line for the men onboard, while the Danes were removing the mast, the Swedes continued shooting at the ship, causing heavy casualties.

[11] The small group of three Danish ships that had sailed from Rönne were only intended to control the waters and make sure the Swedes respected their neighbours, and not for a large sea battle.

The remaining Danish ships in Rönne did not come to help Admiral Jacob Brockenhuus, instead, they stayed at a safe distance and did not participate in the battle.

[11] As a result of their inferior numbers, the Danes suffered a crushing defeat, and when Brockenhuus, realizing that the remaining Danish ships would be destroyed, surrendered to the Swedes.

As a consequence, Frederick and the Danish fleet were seen as the aggressors, and when the war broke out, Eric hoped that the entire world would "pour sympathy" for him.

[18][1] Åke had previously received strict orders from Eric to conquer the Danish holdings in Estonia if war broke out.

[20][1] Åke probably did not dare to meet Gotthard in open battle as the German cavalry in his forces refused to obey the king's orders.

The Polish king dismissed all of his German cavalry in late 1563 and the Poles limited themselves to a careful offensive against the isolated Swedish fortress of Karkus.

[1][22] Eric had large ambitions for Horn, ordering him to capture numerous castles belonging to the Diocese of Riga, the remaining fortresses under Duke John, and Ösel along with the surrounding islands.

Henrik Klasson Horn began the Swedish campaigning by moving against Lode in the beginning of the year and, despite lacking artillery and because no Poles or Tatars intervened, he succeeded in taking it.

[1][22][24] During the siege, the lieutenant of Klaus Kursell, Henrik Dücker, defected to the Poles and joined Kaspar Oldenbokum, under whose command he brought around 200 horsemen.

[1][24][22] Simultaneously, a message from Ösel claimed that Sweden and Denmark had begun peace negotiations, which Horn believed and on 19 February a truce for 2 months between the Swedes and Danes was established.

[24] At the beginning of the year, Swedish forces in Estonia consisted of around 2,467 soldiers[clarification needed] and 907 cavalry according to a muster carried out in January.

[1][25][26][27] Oldenbokum and his men organized a party at one of Pernau's council members, Klas Zinte, who they knew had a key to the city gates hanging in his bedroom at night.

[1][26][27] Henrik Klasson Horn tried on many occasions to assist Pernau, but decided that his forces were too weak to engage in open battle with Oldenbokum.

Two days later, when Oldenbokum was having a party in his camp, Horn decided to commit to a sortie with three Fähnleins and 800 knights; the engagement would be known as the Battle of Obermühlenberg.

[1] To exploit his victory, Horn decided to strike against the weakest point of Danish Estonia, the island of Dagö (modern day Hiiumaa).

[24] Three weeks before Christmas, Horn marched out of Reval and cleared the countryside from raiders, before attacking Pernau; due to the lack of artillery, he initiated a blockade to starve the city.

[1] In March, the Polish king, Sigismund II Augustus, forced Henrik Klasson Horn to lift his blockade of Pernau.

After deliberating with the king for several days, he was sent back to Estonia on 4 December with the task of retaking Pernau or to ravage the Diocese of Riga, the latter being intended to prevent a Polish attack into Swedish territory.

[1][31] Subsequently, he began to fulfill his instructions; he sent Clas Kursell to pillage the Diocese of Riga, where he won a small victory at Lemsal (Limbaži) after he surprised a Polish force.

[1][35] Sjöblad repelled a Danish fleet that was threatening Reval while bringing away merchant ships, before landing Kursell and his men on Ösel on 25 July.