Oscarsborg Fortress: Norway’s Island Guardian & WWII Hero

Oscarsborg’s most famous moment came during World War II, when it played a decisive role in delaying the Nazi invasion of Norway. In the early hours of April 9, 1940, the German heavy cruiser Blücher—carrying over 1,000 troops meant to capture Oslo—entered the fjord. Despite being undermanned and armed with aging artillery, the fortress’s commander, Colonel Birger Eriksen, made a historic decision. Defying orders to stand down, he famously declared: "Either I will be decorated or court-martialed. Fire!" The fortress’s guns struck the Blücher with devastating precision, hitting its ammunition stores and fuel tanks. The final blow came from Oscarsborg’s torpedo battery, which had trained for years with wooden dummy torpedoes—until that fateful morning when they fired live ones. The sinking delayed the Nazi occupation, allowing Norway’s royal family, government, and gold reserves to escape.