Battle of Bornholm ( 1535 ) The Battle of Bornholm was a naval engagement that took place in June 1535 . The conflict saw Lübeck & the Hanseatic League engaged against the forces of Sweden , Prussia , Holstein and Denmark . The Battle of Bornholm was part of the larger Count ' s Feud . Cause of the battle . In June 1535 , Sweden joined with Duke Christian of Gottorp , later crowned King Christian III in the conflict later known as the Count ' s Feud 1534 - 1536 AD . After the Danish King Frederick I died in 1533 , a conflict began between the Danish nobility and their successor , Christian III versus the East Danish Citizenship , led by Copenhagen , Malmö and Landskrona in alliance with Lübeck . Duke Christian allied with his brothers - in - law Albert of Prussia and Gustav Vasa , the king of Sweden . When Sweden joined the conflict , Christian III was fighting on two fronts and desperately needed help . Assembling the fleet . Before sending their fleet to Denmark and Christian III , the Swedish needed an experienced Danish " guide " to assist the Swedish commander , thus Gustav Vasa appointed the Danish noble Peder Skram . He ( Gusvav Vasa ) distrusted Skram and sent an additional letter to the Swedish commander Måns Svensson Some giving him secret orders . It is important to know that an admiral ' s task was not to sail the ship , but command it in battle . In Swedish territory , Måns was commander . Later in Danish waters , Peder Skram had the command of the fleet . The fleet set sail from Stockholm and stopped in Söderköping to stop and bring on board butter . Next , the fleet sold iron in Kalmar and about 1 , 800 soldiers joined . Outside the Swedish island Gotland the Swedish fleet meet the rest of the allies , from Holstein and Prussia . The Prussian fleet was led by Admiral Johan Pein , who contributed with seven warships , of which one ship was large , with a crew of about 900 men . From Holstein , there are no records of how many ships , only that they were small and few . ( 2 small ships ? ) . Allied ships . " Stora Kravelen " commanded by Måns Svensson Some and Peder Skram with about 1 , 000 men " Kamperman " unknown commander , Jacob Bagge a later famous admiral in the Russian war ( 1555 - 1557 ) was on board , but not commander . Lübeck ships . " Michael " unknown commander The Sea Battle of Bornholm . June 8 , the Lübeck ships are sighted outside Bornholm and the battle begins with the largest Swedish ships " Stora Kravelen " and " Kamperman " engaged the large Lübeck ships . " Stora Kravelen " began by attacking " Michael " but got its " fallmast " destroyed and its maneuverability decreased but " Stora Kravelen " was supported by " Kamperman " and during repairing the damages , " Michael " barely avoided being boarded and fled . According to a contemporary information , the " Stora kravelen " could quickly follow up the retreating " Michael " but not board it , thus it was forced to use artillery . Cause of this , the battle of Bornholm is one of the first sea battles fought only with artillery ( cannons ) . When the smaller Prussian and Holstein ships arrived , the Lübeck ships fled the battle . Casualties . " Stora Kravelen " lost 74 men , " Michael " probably lost 2 – 3 times more , all other casualties are unknown . References . Wahlström & Widstrand , " Svenska slagfält " 2005 , page 49 - 54 .