COPENHAGEN HARBOR — Marine archaeologists discovered the wreck of the Danish warship Dannebroge on the seabed of Copenhagen Harbor, announcing the find 225 years to the day after the Battle of Copenhagen in 1801. Divers also recovered part of a sailor's lower jawbone at the site.

Denmark's Viking Ship Museum is leading the monthslong underwater excavation. Marine archaeologists began surveying the area late last year, targeting a spot believed to match the Dannebroge's final position. Divers are working approximately 50 feet beneath the surface in thick sediment and almost zero visibility to unearth the wreck, navigating a dig site full of cannonballs that pose a hazard in waters darkened by silt stirred up from the seabed.

"Sometimes you can't see anything, and then you really have to just feel your way, look with your fingers instead of with your eyes," said Marie Jonsson, a diver and maritime archaeologist. Dendrochronological dating of wooden parts recovered from the wreck matched the year the Dannebroge was built, and the sizes of the wooden parts found at the site matched dimensions shown in historical drawings.

"It's a big part of the Danish national feeling," said Morten Johansen, head of maritime archaeology at the Viking Ship Museum.

In the 1801 Battle of Copenhagen, a British fleet attacked and defeated Denmark's navy, which had formed a protective blockade outside the harbor. The British aimed to force Denmark out of an alliance with Russia, Prussia, and Sweden. Thousands of sailors were killed and wounded during the hourslong naval clash.

The 157-foot Dannebroge served as the Danish flagship, commanded by Commodore Olfert Fischer. During the battle, cannon fire tore through the warship's upper deck, and incendiary shells started a fire aboard the vessel. After being set ablaze, the Dannebroge slowly drifted northward and then exploded. Records say the explosion created a deafening roar heard across Copenhagen.

Johansen described the conditions sailors faced during the battle. "It was a nightmare to be on board one of these ships. When a cannonball hits a ship, it's not the cannonball that does the most damage to the crew, it's wooden splinters flying everywhere, very much like grenade debris," he said.

The excavation site will soon be enveloped by construction work on Lynetteholm, a housing district planned for the middle of Copenhagen Harbor that is expected to be completed by 2070.