The naval Battle of Copenhagen (Danish: Slaget på Reden) was fought on April 2, 1801 by a British fleet under the command of Admiral Sir Hyde Parker, against a Dano-Norwegian fleet anchored just off Copenhagen. The main attack was led by Vice-Admiral Horatio Nelson, who famously disobeyed Parker's order to withdraw and destroyed many of the Dano-Norwegian ships before Denmark-Norway agreed to a truce.
The battle was due to multiple failures of diplomacy in the latter half of 1800 and the beginning of 1801 during the Napoleonic wars. One of Great Britain's principal advantages against France was naval superiority and its ability to control sea traffic to France. The eccentric Russian Tsar Paul, after having been a British ally, arranged an Armed Neutrality of Scandinavia, Prussia, and Russia to enforce free trade. This was perceived by the United Kingdom to be very much in the French interest and a serious threat to her existence, particularly because it threatened the supply of timber and naval stores from Scandinavia.