Helgoland (Helgoland), was a British possession from 1807 – 1890.

Flag of British Heligoland

On 11 September 1807, during the Napoleonic Wars, HMS Carrier brought to the British Admiralty the despatches from Admiral Thomas McNamara Russell announcing Heligoland’s capitulation to the British. Heligoland became a centre of smuggling and espionage against Napoleon.
Denmark then formally ceded Heligoland to the United Kingdom by the Treaty of Kiel (14 January 1814). Thousands of Germans came to Britain and joined the King’s German Legion via Heligoland.
In 1826, Heligoland became a seaside spa and soon it turned into a popular tourist resort for the German upper-class. The island also attracted artists and writers, especially from Germany and even Austria who enjoyed the freedom of the benignly ruled (British) island, including Heinrich Heine and August Heinrich Hoffmann von Fallersleben. It was a refuge for revolutionaries of the 1830 and 1848 German revolutions. Britain gave up the islands to Germany in 1890 in the Heligoland-Zanzibar Treaty.

Denmark was forced to join Napoleon’s Continental System which was designed to enforce a trading embargo and blockade against the British. The admiralty, in the days after Trafalgar, were keen to acquire the Heligoland to help facilitate smuggling to the ports on the Continent.
The Danish garrison could do little to resist the Royal Navy arrived and surrendered without firing a shot. The only setback for the British was when one of the ships (a bomb-ketch named HMS

Map of Heligoland (Helgoland), 1900

Explosion) broke free from its moorings and ran aground on nearby Sandy Island. The islanders helped the sailors salvage what they could and it was to be Explosions foremast that provided the flagpole with which to claim the island for the British.

The island remained useful to the Royal Navy for the remainder of the Napoleonic Wars, though its continued ownership after the war was by no means guaranteed. Heligoland would find itself a bargaining chip along with other Danish and territories. Britain was keen to keep Heligoland though returned other Danish islands under the Treaty of Kiel. This would be the start of British ownership for the next 76 years.
The island took on a growing strategic importance for the Germans with the construction of the Kiel canal linking the Baltic Sea to the North Sea. The Germans saw that the island cpould be used as a base for the Royal Navy to launch an attack on the Kiel Canal, Kaiser Wilhelm II had called for the islands accession into the German Empire.

The British, under Salisbury, were willing to consider a trade for the island with an elaborate deal to increase Britain’s influence and control in Central and Eastern Africa.
Britain was to receive primacy in Uganda, Kenya, and Zanzibar in return for the island. Queen Victoria herself was less than impressed with the trade and did attempt to scupper it.
However, Salisbury managed to convince her of the merits of the deal and persevered in seeing it through. The Heligolanders were not consulted over the islands sovereignty.

Handover of Heligoland 1890

On the 9th August, 1890, the Union Jack was taken down, the following day the Kaiser arrived on the island and claimed it for Germany. The island was duly militarised and turned into a German naval and then later a submarine base.

Heligoland would have been a useful base to monitor the German fleets, though the admiralty were convinced that it was probably too isolated from Britain and too close to Germany to actually defend. The first naval skirmish of the First World War was very close to the island and the biggest Battle of Jutland was not that far away from the islands.
In the Second World War, the British would launch a thousand bomber raid on the island to destroy the military infrastructure of the island.

The islands returned to British control on two separate occasions. At the end of both World Wars, the British became responsible for its administration. The British oversaw the dismantlement of the German fortifications from 1920 to 1922 as part of the Treaty of Versailles.

After the Second World War, the islands were administered as part of the North German occupation zone allocated to the British from 1945 to 1952. The islanders were evacuated and it was used as a testing ground for the British military until it was handed back to the Germans.