The Second Battle of Copenhagen (or the Bombardment of Copenhagen) (16 August – 7 September 1807) was a British bombardment of the Danish capital, Copenhagen, in order to capture or destroy the Dano-Norwegian fleet during the Napoleonic Wars. The incident led to the outbreak of the Anglo-Russian War of 1807, which ended with the Treaty of Örebro in 1812. The attack on Denmark, a neutral country, was heavily criticized internationally.
Britain's first response to Napoleon's Continental System was to launch a major naval attack on Denmark. Although neutral, Denmark was under French pressure to pledge its fleet to Napoleon. In September 1807, the Royal Navy bombarded Copenhagen, seizing the Danish fleet and assured use of the sea lanes in the North Sea and Baltic Sea for the British merchant fleet. A consequence of the attack was that Denmark did join the Continental System and the war on the side of France, but without a fleet it had little to offer.
The attack gave rise to the term to Copenhagenize.
Background
Despite the defeat and loss of many ships in the first Battle of Copenhagen in 1801, Denmark-Norway, possessing Jutland, Norway, Greenland, Schleswig-Holstein, Iceland and several smaller territories, still maintained a considerable navy. The majority of the Danish Army, under the Crown Prince, was at this time defending the southern border against possible attack from the French.
There was concern in Britain that Napoleon might try to force Denmark to close the Baltic Sea to British ships, perhaps by marching French troops into Zealand. The British believed that access to the Baltic was "vitally important to Britain" for trade as well as a major source of necessary raw materials for building and maintaining warships and that it gave the Royal Navy access to help Britain's allies Sweden and (before Tilsit) Russia against France. The British thought that after Prussia had been defeated in December 1806, Denmark's independence looked increasingly under threat from France. George Canning's predecessor as Foreign Secretary, Lord Howick, had tried unsuccessfully to persuade Denmark into a secret alliance with Britain and Sweden.
On 21 January 1808, Lord Hawkesbury told the House of Lords that he had received information from someone on the Continent "that there were secret engagements in the Treaty of Tilsit to employ the navies of Denmark and Portugal against this country". He refused to publish the source because he said it would endanger their lives.
The reports of French diplomats and merchants in northern Europe made the British government uneasy, and by mid-July, the British believed that the French intended to invade Holstein in order to use Denmark against Britain. Some reports suggested that the Danes had secretly agreed to this. The Cabinet decided to act, and on 14 July Lord Mulgrave obtained from the King permission to send a naval force of 21 to 22 ships to the Kattegat for surveillance of the Danish navy in order to pursue "prompt and vigorous operations" if that seemed necessary. The Cabinet decided on 18 July to send Francis Jackson on a secret mission to Copenhagen to persuade Denmark to give its fleet to Britain. That same day, the Admiralty issued an order for more than 50 ships to sail for "particular service" under Admiral James Gambier. On 19 July, Lord Castlereagh, the Secretary of State for War and the Colonies, ordered General Lord Cathcart at Stralsund to go with his troops to the Sound where they would get reinforcements.
During the night of 21/22 July, Canning received intelligence from Tilsit that Napoleon had tried to persuade Alexander I of Russia to form a maritime league with Denmark and Portugal against Britain. Spencer Perceval, the Chancellor of the Exchequer, wrote a memorandum setting out the government's case for sending forces to Copenhagen: "The intelligence from so many and such various sources" that Napoleon's intent was to force Denmark into war against Britain could not be doubted. "Nay, the fact that he has openly avowed such intention in an interview with the Emperor of Russia is brought to this country in such a way as it cannot be doubted. Under such circumstances it would be madness, it would be idiotic... to wait for an overt act". Historian Hilary Barnes notes that Canning had no knowledge of the secret articles of the Treaty of Tilsit. He argues that Canning's decision was "rash, calamitous, and lacking in understanding of the Danes and of Danish foreign policy."