In 1940, the Norwegian navy consisted of two armored coast defense ships launched in 1900 and forming the Panserskipsdivisjon (armored ship division). Two other older coast defense ships lay disarmed at Horten, a naval base outside of Oslo. The first two would be sunk at Narvik in 1940, and the latter two would be captured by the Germans and rearmed as antiaircraft guardships. In terms of modern ships, Norway had a minelayer and four 600-ton torpedo boats. Several destroyers and torpedo boats were under construction at the time of the German attack. The remainder of the fleet consisted of 4 destroyers and 11 torpedo boats, all built before 1920; 9 submarines, and miscellaneous warships, one of which dated from 1858!
Commander of the navy Rear Admiral H. E. Diesen was viewed as a political admiral. The officer corps had been gutted in the early 1930s as a consequence of budgetary constraints, and a substantial element within it supported Vidkun Quisling's Norwegian Nazi Party. However, most officers rallied to king and country when Germany invaded.
The dramatic event for the Norwegian navy in the war was the German invasion of Norway in April 1940. It was a surprise on two levels. It was a strategic surprise, as Norwegian leaders were more concerned by an invasion or limited naval action by the Allies, primarily the British navy. They did not foresee an attack from the smaller Germany, which would not have command of the seas. The Germans also achieved surprise at the operational level, although a steady stream of warnings of German warships and troopships moving north arrived in the hours before the attack.
After two months of fighting, 13 warships of the Norwegian navy and about 500 officers and sailors reached British ports. Only one of these ships was modern. The remaining Norwegian naval vessels were either sunk or incorporated into the German navy. The Norwegian navy used its older warships for training and patrol and minesweeping operations, and the Norwegian government-in-exile added to these ships more than 50 whaling ships that had been operating in the polar regions when Norway had been invaded. These 300- to 500-ton ships saw British and Norwegian service as minesweepers and in clandestine operations. More than 200 of the latter operations occurred in Norwegian waters as part of the "Shetland Bus."
During the war, the Norwegian navy secured under Lend-Lease 5 U.S. World War I–era destroyers and 7 British-built destroyers. It obtained an additional 3 submarines, 7 corvettes, 3 submarine chasers, and 1 patrol craft, together with 29 motor torpedo and motor launches that saw much action in the Channel and in Norwegian coastal waters.
Norwegian navy ships participated in the Battle of the Atlantic, helped protect the convoys to Murmansk, and took part in Operations torch and overlord. Of major combatants, Norway lost in battle 1 submarine while attempting to land agents in Norway, as well as 2 destroyers and 3 corvettes in the Atlantic. The Norwegian navy also operated a modest naval air arm from Scotland for patrols in the Norwegian and North Seas.
Norway's greatest contribution at sea during the war was its merchant marine. The fourth largest in the world, it amounted to more than 1,000 ships totaling more than 4.8 million tons. These supplied valuable revenue to the government-in-exile in London, but over 500 ships were lost in the course of the war. By 1945, Norway emerged with an effective and sizeable navy ready to help lead the way into collective military action under the banner of the North Atlantic Treaty Organization.
Moulton, J. L. The Norwegian Campaign of 1940: A Study of Warfare in Three Dimensions. London: Eyre and Spottiswoode, 1966.; Salmon, Patrick, ed. Britain and Norway in the Second World War. London: Her Majesty's Stationery Office, 1995.