HNoMS Æger was a Sleipner-class destroyer launched at Karljohansvern naval shipyard in Horten in 1936. The Sleipner class was part of a Norwegian rearmament scheme started as war became ever more likely in the 1930s. When the Germans invaded Norway on 9 April 1940, Æger intercepted and sank the clandestine German supply ship Roda. She was shortly afterwards attacked and sunk by German bombers, claiming two of the attacking aircraft with her anti-aircraft armament before being taken out of action by a heavy bomb. This makes her the first naval ship sunk by aeroplane in hostility.

Operation Weserübung was the invasion of Denmark and Norway by Nazi Germany during the Second World War and the opening operation of the Norwegian Campaign.