In early October 1710, during the Great Northern War, a Danish and a Swedish fleet engaged in a battle that brought losses to both sides, including the Danish warship Dannebroge and the two Swedish line ships Tre Kronor (“Three Crowns”) and the Princess Ulrika Eleonora.
The Danish naval force, under the command of Admiral Ulrik C. Gyldenløve, son of King Christian V, was anchored in the inner part of Køge Bay south of Copenhagen. The Danish fleet was awaiting the arrival of transport vessels sent to fetch Russian soldiers in Gdansk. The fleet’s journey to Gdansk was interrupted, however, and in early October was on its way back to Denmark.
Because winter was imminent, Admiral Gyldenløve assumed that his ship was safe in the bay. He did not believe that the Swedes commanded by Admiral Hans Wachmeister would leave their sheltered harbour in Karlskrona so close to the arrival of winter. Gyldenløve was so certain, he did not even send his reconnaissance ships to keep an eye on the Swedish fleet. He also missed alarming reports from Christiansø, north of Bornholm, that the Swedish navy has eased its anchor.
The Swedish navy’s intention for the trip was to cut off the Danish transport fleet’s passage back to Denmark and sink the ships before they arrived.
On the morning of 4 October, Gyldenløve and his sailors could see several ships approaching Køge Bay. At first, they thought it was the expected transport fleet that had arrived and not the Swedish fleet. When they realised their mistake, a flurry of activity erupted on the Danish ships. The anchor ropes were cut to quickly get the vessels settled into formation before the inevitable battle. The Swedes, too, were surprised because they did not expect the Danish fleet to be at anchor in Køge Bay.
The Dannebroge explodes
In the ensuing battle the Danish line ship Dannebroge catches fire, and when the flames reach the gunpowder storage after nearly two hours the ship explodes. At the same time, two Swedish warships, the Tre Kronor and the Princess Ulrika Eleonora, are abandoned and set on fire. As the Dannebroge explodes and the wind gathers, the fighting ceases and the ships anchor. The harsh weather continues the following day, so there is no fighting. On 6 October, the weather takes a turn for the better but the battles do not resume. However, upon the arrival of the Danish transport fleet several of these ships are burned by the Swedes before the Swedish fleet heads for home.
The Battle of Køge Bay in 1710 is considered to have ended indecisively, with no clear winner. But the Swedes seemed satisfied, since their goal of stopping the Danish transport fleet had been achieved.