[1] At the start of World War II, the UK imposed strict export controls on Icelandic goods, preventing profitable shipments to Germany, as part of its naval blockade.

The initial force of 746 Royal Marines commanded by Colonel Robert Sturges disembarked at the capital Reykjavík.

Meeting no resistance, the troops moved quickly to disable communication networks, secure strategic locations, and arrest German citizens.

Requisitioning local transport, the troops moved to nearby Hvalfjörður, Kaldaðarnes, Sandskeið, and Akranes to secure potential landing areas against the possibility of a German counterattack.

After the German invasion of Denmark and Norway, the British government became increasingly concerned that Germany would soon try to establish a military presence in Iceland.

A surer and more effective solution was to land troops unannounced and present the Icelandic government with a fait accompli.

[7] Much of the planning was conducted en route; the force was supplied with few maps, most of poor quality, with one of them having been drawn from memory.

[citation needed] To guard against a German counter-attack by sea, they would secure the harbour and send troops by land to nearby Hvalfjörður.

[12] On 3 May 1940, the 2nd Royal Marine Battalion in Bisley, Surrey received orders from London to be ready to move at two hours' notice for an unknown destination.

On 4 May, the battalion received some modest additional equipment in the form of Bren light machine guns, anti-tank rifles, and 2-inch mortars (51 mm).

[16] He was accompanied by a small intelligence detachment commanded by Major Humphrey Quill and a diplomatic mission managed by Charles Howard Smith.

To avoid drawing attention to itself, the force was divided into two trains for the journey,[19] but due to delays in rail travel, the troops arrived at the railway station in Greenock about the same time, losing the small degree of anonymity desired.

[14] On the morning of 7 May, the force headed to the harbour in Greenock, where they met the cruisers Berwick and Glasgow, which would take them to Iceland.

Very rough seas were encountered on passage to Iceland and the majority of the marines cluttered gangways and mess-decks throughout the ship, prostrate with seasickness.

[26] The principal aim of the flight was to scout the vicinity of Reykjavík for enemy submarines, which the Naval Intelligence Division had convinced itself were operating out of Icelandic harbours.

[26] The Walrus was given orders not to fly over Reykjavík but – either accidentally or as the result of a miscommunication – it flew several circles over the town, making considerable noise.

[27][28] At this time, Iceland possessed only passenger aircraft, which did not fly at night, so this unusual event awoke and alerted a number of people.

The acting chief of police, Einar Arnalds, surmised that it most likely originated from a British warship bringing the expected new ambassador.

[40] He then hastened to report to the Prime Minister, who ordered him not to interfere with the British troops and to try to prevent conflicts between them and Icelanders.

[42] The flyer explained in broken Icelandic that British forces were occupying the city and asked for co-operation in dealing with local Germans.

[45] The British discovered a fire upstairs in the building and found a pile of documents burning in the consul's bathtub.

By requisitioning local transport, the marines managed to deploy across 75km by 6pm, investing a seaplane base (Hvalfjörður) and two potential airstrips (Kaldaðarnes and Sandskeið).

[49] On the evening of 10 May, the government of Iceland issued a protest, charging that its neutrality had been "flagrantly violated" and "its independence infringed", noting that compensation would be expected for all damage done.

The British promised compensation, favourable business agreements, non-interference in Icelandic affairs, and the withdrawal of all forces at the end of the war.

The initial invasion force was ill-equipped, only partially trained and insufficient for the task of occupation and defence of the island.

[14] Over the next two weeks Force Sturges noted a cooling of relations with the local population as concerns grew that the British presence would attract German naval shelling or aerial bombing.

The UK invaded to forestall a German occupation, to provide a base for naval and air patrols, and to protect merchant shipping lanes from North America to Europe.

The occupation required the building of a network of roads, hospitals, harbours, airfields and bridges that had an enormous positive economic impact.

The Icelanders severely censured the sexual relationships between troops and local women, which were causing considerable controversy and political turmoil.

In a postwar interview, Walter Warlimont claimed that "Hitler definitely was interested in occupying Iceland prior to [British] occupation.