In 1956, sea area Heligoland became German Bight. But why did the North Sea island, which for nearly a century had demonstrated its loyalty to Britain, lose its identity? How had this once peaceful haven become, as Admiral Jacky Fisher exclaimed "a dagger pointed at England’s heart"? Behind the renaming of Heligoland lies a catalogue of deceit, political amibition, blunder, and daring. Heligoland came under British rule in the nineteenth century, a "Gibraltar" of the North Sea. Then, in 1890, despite the islanders’ wishes, Lord Salisbury announced his intention to swap it for Germany’s presence in Zanzibar. The Prime Minister’s decision unleashed a storm of controversy. Queen Victoria telegrammed from Balmoral to register her fury. During both world wars, it was used by Germany to control the North Sea, and RAF planes bombed the once-British territory. The story of Heligoland is more than an obscure footnote to the British Empire—it shows the significance of territory throughout history.