'Grünpfeil' was the German seizure and occupation of the Channel Islands group, off the west coast of the Cotentin peninsula of northern France, in the aftermath of the fall of France (30 June/4 July 1940).

On 15 June 1940 the British government had decided that the Channel Islands were of no strategic importance and could not, in any event, be held against German forces in occupied France only a few miles distant. However, the British government did not communicate this fact. Included in the British government’s thinking was the feeling that should the Germans occupy the Channel Islands, they would find that their occupation represented little more than a drain on their resources. As it was, the large numbers of troops sent to hold and then to defend the Channel Islands were not available for the defence of strategically more important areas such as the west coast of Europe.

The British government consulted the Channel Islands' elected government representatives to formulate a an evacuation policy. Opinion was divided and, when no overall policy was agreed, there followed a considerable degree of chaos as different policies were adopted by the different islands. The British government concluded that the best policy was to make available as many ships as possible so that Channel Islanders had the option to leave if they so desired.

Alderney recommended that all its population depart, and the Dame of Sark encouraged everyone to stay on Sark. Guernsey evacuated all children of school age, giving their parents the option of keeping their children with them, or evacuating with their school. In Jersey, the majority of the population opted to stay.

Since they did not know that the Channel Islands had no military presence, the Germans approached the islands cautiously. The results of reconnaissance flights were inconclusive, and on 28 June 1940 German bombers attacked the harbours of St Peter Port on Guernsey and St Helier on Jersey. In St Peter Port, what the reconnaissance had mistaken for troop carriers was in fact lines of lorries queued up to load tomatoes for export to England. Some 44 islanders were killed in the raids.

While the German army prepared to land an assault force of two battalions on the Channel Islands, a reconnaissance pilot landed in Guernsey on 30 June, and the island officially surrendered to this officer. Jersey surrendered on 1 July. Alderney, where no one remained, was occupied on 2 July, and a small detachment travelled from Guernsey to Sark, which officially surrendered on 4 July.

The Germans quickly consolidated their positions, bringing in more infantry, establishing communications, siting Flak batteries, setting up an air link with the French mainland, and rounding up any British servicemen on leave in the islands.