The Battle of Copenhagen (Danish: Slaget på Reden) occurred on 2 April 1801 during the War of the Second Coalition when a British naval fleet under the command of Admiral Sir Hyde Parker defeated a Danish fleet anchored just off Copenhagen. The Danish fleet at the inlet to Copenhagen harbour formed a blockade preventing the British fleet to enter the harbour. All these ships were old anyway. Denmark should defend her Capital with these ships and bastions on both side of the harbour inlet, Kastellet, Trekroner, Lynetten (which all still exists) as well as Quintus, Sixtus and Strickers.
It was the second attempt from the Brittish to scare Denmark, as The Brittish already in August 1800 had entered Øresund with a navy, in order to force Denmark to sign an alliance with Denmark. Now Britain would have Denmark’s entire navy and merchant fleet, so it wouldn’t fall in to the hands of the French. But the British were not aware that of the fact that the modern Royal Danish Navy and many merchant ships were well hidden in the Roskilde fjord, a bluff which never was called by the British. Vice Admiral Horatio Nelson led the main attack. He famously is reputed to have disobeyed Sir Hyde Parker’s order to withdraw by holding the telescope to his blind eye to look at the signals from Parker. Parker’s signals had given Nelson permission to withdraw at his discretion, yet he declined. Copenhagen is often considered to be Nelson’s hardest-fought victory, ranked among battles such as the Battle of Trafalgar, as the Danes offered a very stubborn resistance.