Operation Weserübung

Following a meeting with Vidkun Quisling from Norway on December 14th,[7] Hitler turned his attention to Scandinavia. Convinced of the threat posed by the Allies to the iron ore supply, Hitler ordered the Oberkommando der Wehrmacht (Armed Forces High Command; OKW) to begin preliminary planning for an invasion of Norway. The preliminary plan was named Studie Nord and called for only one army division.

Between 14 and 19 January, the Kriegsmarine developed an expanded version of this plan. It decided upon two key factors: surprise was essential to reduce the threat of Norwegian resistance (and British intervention), and faster German warships, rather than comparatively slow merchant ships, should be used as troop transports. That would allow all targets to be occupied simultaneously, which was impossible if transport ships were used since they travelled only slowly. The new plan called for a full army corps, including a mountain division, an airborne division, a motorized rifle brigade and two infantry divisions. The target objectives of the force were the Norwegian capital, Oslo, and other population centres: Bergen, Narvik, Tromsø, Trondheim, Kristiansand and Stavanger. The plan also called for the swift capture of the Kings of Denmark and Norway in the hope of triggering a rapid surrender.

On 21 February 1940, command of the operation was given to General Nikolaus von Falkenhorst. He had fought in Finland during the First World War and was familiar with Arctic warfare, but he would have command of only the ground forces, despite Hitler's desire to have a unified command.

The final plan was codenamed "Operation Weserübung" on 27 January 1940. The ground forces would be the XXI Army Corps, including the 3rd Mountain Division and five infantry divisions;none of the latter had yet been tested in battle. The first phase would consist of three divisions for the assault, with the remainder to follow in the next wave. Three companies of paratroopers would be used to seize airfields. The decision to also send the 2nd Mountain Division was made later.

Almost all U-boat operations in the Atlantic were to be stopped for the submarines to aid in the operation. All available submarines, including some training boats, were used as part of Operation Hartmut in support of Operation Weserübung.

Initially, the plan was to invade Norway and to gain control of Danish airfields by diplomatic means. However, Hitler issued a new directive on 1 March that called for the invasion of both Norway and Denmark. That came at the insistence of the Luftwaffe to capture fighter bases and sites for air warning stations. The XXXI Corps, formed for the invasion of Denmark, consisted of two infantry divisions and the 11th motorized brigade. The entire operation would be supported by the X Air Corps, which consisted of some 1,000 aircraft of various types.

German dead being brought ashore from the German naval tanker Altmark.

The heavy cruiser Admiral Hipper landing troops in Norway in 1940.

In February, the Royal Navy destroyer HMS Cossack boarded the German transport ship Altmark in Norwegian waters. That itself violated Norwegian neutrality. The Altmark rescued British prisoners-of-war, which also violated Norwegian neutrality since she was obliged to release them as soon as she entered neutral territory. Hitler regarded that response to German violation of Norwegian neutrality as a clear sign that the Allies were also willing to violate Norwegian neutrality. That made him become even more strongly committed to the invasion.[6]

On 12 March, the United Kingdom decided to send an expeditionary force to Norway just as the Winter War was winding down. The expeditionary force began boarding on 13 March, but it was recalled and the operation cancelled because of the end of the Winter War. Instead, the British Cabinet voted to proceed with the mining operation in Norwegian waters, followed by troop landings.

The first German ships set sail for the invasion on 3 April. Two days later, the long-planned Operation Wilfred was put into action, and the Royal Navy detachment, led by the battlecruiser HMS Renown, left Scapa Flow to mine Norwegian waters. The mine fields were laid in the Vestfjorden in the early morning of 8 April. Operation Wilfred was over, but later that day, the destroyer HMS Glowworm, which detached on 7 April to search for a man lost overboard, was lost in action to the German heavy cruiser Admiral Hipper and two destroyers belonging to the German invasion fleet.

On 9 April, the German invasion was under way, and the execution of Plan R 4 was promptly started.

The operation's military headquarters was Hotel Esplanade in Hamburg, where orders were given to, among others, the air units involved in the invasion.[12]

Norway was important to Germany for two primary reasons: as a base for naval units, including U-boats, to weaken Allied shipping in the North Atlantic, and to secure shipments of iron ore from Sweden through the port of Narvik.[6] The long northern coastline was an excellent place to launch U-boat operations into the North Atlantic to attack British commerce. Germany was dependent on iron ore from Sweden and was worried, with justification, that the Allies would attempt to disrupt those shipments, 90% of which originating from Narvik.

The invasion of Norway was given to the XXI Army Corps under General Nikolaus von Falkenhorst and consisted of the following main units:

• 69th Infantry Division
• 163rd Infantry Division
• 181st Infantry Division
• 196th Infantry Division
• 214th Infantry Division
• 3rd Mountain Division

The initial invasion force was transported in several groups by ships of the Kriegsmarine:

1. Battleships Scharnhorst and Gneisenau as distant cover, plus 10 destroyers with 2,000 Gebirgsjäger (mountain infantry) under General Eduard Dietl to Narvik
2. Heavy cruiser Admiral Hipper and four destroyers with 1,700 troops to Trondheim
3. Light cruisers Köln and Königsberg, artillery training ship Bremse, Schnellboot mothership Karl Peters, two torpedo boats and five motor torpedo boats with 1,900 troops to Bergen
4. Light cruiser Karlsruhe, three torpedo boats, seven motor torpedo boats and Schnellboot mothership (Schnellbootbegleitschiff) Tsingtau with 1,100 troops to Kristiansand and Arendal
5. Heavy cruiser Blücher, heavy cruiser Lützow, light cruiser Emden, three torpedo boats and eight minesweepers with 2,000 troops to Oslo
6. Four minesweepers with 150 troops to Egersund

The German landing sites during the initial phase of Operation Weserübung

Map of Oslofjord with Oscarsborg

Shortly after noon on 8 April, the clandestine German troopship SS Rio de Janeiro was sunk off Lillesand by the Polish submarine ORP Orzeł, part of the Royal Navy's 2nd Submarine Flotilla. However, the news of the sinking reached the appropriate levels of officialdom in Oslo too late to do much more than trigger a limited, last-minute alert. Late in the evening of 8 April 1940, Kampfgruppe 5 was spotted by the Norwegian guard vessel Pol III. Pol III was fired at; her captain Leif Welding-Olsen became the first Norwegian killed in action during the invasion. German ships then sailed up the Oslofjord leading to the Norwegian capital, reaching the Drøbak Narrows (Drøbaksundet).

In the early morning of 9 April, the gunners at Oscarsborg Fortress fired on the leading ship, Blücher, which had been illuminated by spotlights at about 04:15. Two of the fortress guns were 48-year-old German-made Krupp guns (nicknamed Moses and Aron) of 280 mm (11 in) caliber. Within two hours, the badly damaged ship, unable to manoeuvre in the narrow fjord from multiple artillery and torpedo hits, sank with very heavy loss of life totalling 600–1,000 men. The threat from the fortress (and the mistaken belief that mines had contributed to the sinking) delayed the rest of the naval invasion group long enough for the Royal Family, the Cabinet and members of Parliament to be evacuated, along with the national treasury. On their flight northward by special train, the court encountered the Battle of Midtskogen and bombs at Elverum and Nybergsund. As the Norwegian king and his legitimate government were not captured, Norway never surrendered in a legal sense to the Germans, leaving the Quisling government illegitimate. The Norwegian government-in-exile based in London remained, therefore, an Allied nation in the war.

At 7:06pm 5 Norwegian fighters were sent into battle to combat a wave of 70–80 enemy planes. German airborne troops landed at the Oslo airport Fornebu, Kristiansand airport Kjevik, and Sola Air Station – the latter constituting the first opposed paratrooper attack in history;[6] coincidentally, among the Luftwaffe pilots landing at Kjevik was Reinhard Heydrich. Vidkun Quisling's radio-effected coup d'etat at 7.30pm on 9 April[13] was another first. At 8.30pm the Norwegian destroyer Æger was attacked and sunk outside Stavanger by ten Junkers Ju 88 bombers, after it sank the German cargo ship MS Roda. Roda was a carrying a clandestine cargo of anti-aircraft artillery and ammunition for the German invasion force. Bergen, Stavanger, Egersund, Kristiansand, Arendal, Horten, Trondheim and Narvik were attacked and occupied within 24 hours. Ineffective resistance by the Norwegian armoured coastal defence ships Norge and Eidsvold took place at Narvik. Both ships were torpedoed and sunk with great loss of life. The First Battle of Narvik took place between the Royal Navy and the Kriegsmarine on 9 April.[14] The German force took Narvik and landed the 2,000 mountain infantry, but a British naval counter-attack by the modernised battleship HMS Warspite and a flotilla of destroyers over several days succeeded in sinking all ten German destroyers once they ran out of fuel and ammunition.

The towns Nybergsund, Elverum, Åndalsnes, Molde, Kristiansund N, Steinkjer, Namsos, Bodø, and Narvik were devastated by German bombing; some of them were tactically bombed, others terror-bombed. The main German land campaign advanced northward from Oslo with superior equipment; Norwegian soldiers with turn-of-the-century weapons, along with some British and French troops, stop invaders for a time before yielding; this was the first land combat between the British Army and the Wehrmacht in World War II. In the Second Naval Battle of Narvik, the Royal Navy defeated the Kriegsmarine on 13 April.[15]

In land battles at Narvik, Norwegian and Allied forces under General Carl Gustav Fleischer achieved the first major tactical victory against the Wehrmacht in WWII. German forces then overpowered Norwegian troops at Gratangen. The King and his cabinet evacuated from Molde to Tromsø on 29 April, and the Allies evacuated from Åndalsnes on 1 May. Resistance in Southern Norway then came to an end.

Hegra Fortress continued to resist German attacks until 5 May – it was of Allied propaganda importance, like Narvik. King Haakon, Crown Prince Olav, and the Cabinet Nygaardsvold left from Tromsø 7 June aboard the British cruiser HMS Devonshire to represent Norway in exile. The King would return to Oslo on that exact date five years later. Crown Princess Märtha and children, denied asylum in her native Sweden, later left from Petsamo, Finland, to live in exile in the United States. The Norwegian Army in mainland Norway capitulated on 10 June 1940, two months after Wesertag. That made Norway the occupied country that had withstood a German invasion for the longest time before succumbing. Despite the surrender of the main Norwegian forces, the Royal Norwegian Navy and other armed forces continued fighting the Germans abroad and at home until the German capitulation on 8 May 1945.

In the far north, Norwegian, French and Polish troops, supported by the Royal Navy and the Royal Air Force (RAF), fought against the Germans over the control of the Norwegian harbour Narvik, important for the year-round export of Swedish iron ore. The Germans were driven out of Narvik on 28 May, but the deteriorating situation on the European continent made the Allied troops withdraw in Operation Alphabet, and on 9 June, the Germans recaptured Narvik, which was also now abandoned by civilians because of massive Luftwaffe bombing.