Oslofjorden, Battle of, Norway, 1940

The Battle of Drøbak Sound took place in Drøbak Sound, the northernmost part of the outer Oslofjord in south-eastern Norway, on 9 April 1940. It marked the end of the "Phoney War" and the beginning of World War II in Western Europe. A small fleet of the Nazi German navy (the Kriegsmarine) led by the heavy cruiser Blücher was dispatched up the Oslofjord to begin the German invasion of Norway, to seize the Norwegian capital Oslo and capture King Haakon VII and his government. The fleet was engaged in the fjord by Oscarsborg Fortress, an aging coastal installation near Drøbak, that had been relegated to training coastal artillery servicemen – leading the Germans to disregard its defensive value. However, unbeknownst to German military intelligence, the fortress' most powerful weapon was a torpedo battery, which would be used to great effect against the German invaders. The fortress' armaments worked flawlessly despite their age, sinking the Blücher in the fjord and forcing the rest of the German fleet to withdraw. The loss of the German flagship, which carried most of the troops and Gestapo agents intended to occupy Oslo, delayed the German occupation long enough for King Haakon and his government to escape from the capital.