Oscarsborg Fortress’ location, in the middle of the Oslofjord narrows, is a natural defensive position. The fortress has guarded the entrance to Christiania and Oslo for centuries. Oscarsborg became an icon to Norway’s freedom because of the events during the early hours of April 9 1940 when Col. Eriksen and his men sank the German cruiser ‘Blücher’. This courageous action was the single most important reason that the Royal Family and Government were able to escape the clutches of the invading forces.