German invasion of Denmark (1940) in the context of "Invasion of Iceland"

On 10 May 1940, during World War II, the United Kingdom landed Royal Navy and Royal Marines forces at Reykjavík and occupied Iceland without resistance. The operation, codenamed Operation Fork, was launched after Germany's rapid conquest of Denmark, to which Iceland was linked by a personal union, and amid British fears that Germany might establish bases on the strategically important island. Iceland had declared neutrality at the start of the war and rejected British requests for cooperation, but the UK proceeded with an unannounced landing to pre-empt any German move.

British troops quickly secured Reykjavík, detained German nationals, and occupied key communication and transport sites before spreading out to potential landing grounds and harbours. Iceland issued a formal protest against the violation of its neutrality, while Britain promised compensation, non-interference, and eventual withdrawal. Over the following months the initial marine detachment was replaced by British, Canadian, and later American forces, whose presence—eventually numbering tens of thousands—had lasting military, economic, and social effects on the country.