Given their strategic locations regarding Britain and Russia, the Nordic countries in World War II were the targets of German conquest or control, along with the nearby islands, while the British tried to stop them. Finland fought two wars against the Soviet Union and one against Germany, while Denmark and Norway were invaded and occupied by Germany. Iceland and the other islands were under British or American occupation, as was Greenland. Only Sweden managed to remain neutral, cooperating with both belligerent factions.
The main military and naval operations were against Norway, and against Allied convoys headed to the Soviet Union.
The Orkney Islands remained under tight British control. The Royal Navy’s main base was at Scapa Flow.
The Shetland Islands remained under tight British control. It became the base of operations of a Norwegian naval unit nicknamed the "Shetland bus." It used Norwegian fishing vessels with Norwegian crews to conduct espionage and sabotage operations on the coast of Norway.
After Denmark was invaded, the British Navy made a pre-emptive, but friendly, invasion and occupation of the Faroes to prevent a German invasion.