In 1564, Mars was the largest warship of the entire Baltic Sea. Erik XIV had it built to outshine anything that an enemy could possibly accomplish. But Mars only had time for a single battle, at the northern tip of Öland in May 1564. When the Swedish naval fleet encountered the allied forces of Denmark and Lübeck, the losses were great for both sides.
Admiral Jakob Bagge gathered his fleet in Stockholm’s southern archipelago in May 1564. On board the 38 Swedish ships were roughly 5,100 sailors and soldiers. Mars was a brand-new warship at the time, fitted with many guns.
The two fleets met at the northern tip of Öland in the middle of the day on 30 May. When the sun went down, the Danish admiral ship Fortuna was badly damaged and the Lübeckian ship Lange Bark had been sunk.
Early the next morning, the battle resumed. Danish and Lübeckian ships managed to take over Mars and board the ship. Bloody skirmishes at close quarters erupted and the Swedes were forced to surrender. Soon after, Mars exploded and about 800–1,000 sailors and soldiers from both sides perished.
In 2011, the remains of a large ship were found at a depth of 75 metres at the northern tip of Öland. The foresection was blown off and the damaged hull lay on its side. There were several guns at the wreck site, and one of them was identified. It was manufactured on 1 May 1564 and loaded aboard Mars on 11 May of that year. This helped to establish the identity of the wreck.