Operation Weserübung (Unternehmen Weserübung [ˈveːzɐˌʔyːbʊŋ], (German: "Operation Weser Exercise") was the invasion of Denmark and Norway by Nazi Germany during World War II. Taking place from 9 April – 10 June 1940, it was the opening operation of the Norwegian Campaign.
In the early morning of 9 April 1940 (Wesertag, "Weser Day"), German forces occupied Denmark and invaded Norway, ostensibly as a preventive manoeuvre against a planned Anglo-French occupation of Norway known as Plan R 4, which developed as a response to a German invasion of Norwegian territory. After the rapid occupation of Denmark, in which the Danish military was ordered to stand down as Denmark's government did not declare war with Germany, German envoys informed the governments of Denmark and Norway that Germany's forces had come to protect both countries against Anglo-French attacks. Significant differences in geography, location and climate between the two nations made the actual military operations very dissimilar.
The invasion fleet's nominal landing time, Weserzeit (Weser Time), was set to 05:15.
Background
By the spring of 1939, the British Admiralty began to view Scandinavia as a potential theatre of war in a future conflict with Nazi Germany. However, the British government was reluctant to engage in another land conflict on the continent in the belief that it would repeat World War I. Therefore, the British began to consider naval blockades against Germany if war broke out. German industry was heavily dependent on the import of iron ore from mines in Swedish Lapland, and most of that ore was shipped through the ice-free Norwegian port of Narvik. Control of the Norwegian coast would serve to tighten a potential blockade against Germany.
In October 1939, the chief of the Kriegsmarine, Grand-Admiral Erich Raeder, discussed with Adolf Hitler the danger posed by potential Allied bases in Norway and the possibility of Germany pre-emptively seizing those locations. The Kriegsmarine argued that a German occupation of Norway would allow control of the nearby seas and serve as a platform for staging submarine operations against the Allies. However, the other branches of the Wehrmacht were not interested, and Hitler issued a directive stating that the main effort would be a land offensive through the Low Countries.
Toward the end of November 1939, Winston Churchill, as a new member of the Chamberlain war ministry, proposed the mining of Norwegian waters in Operation Wilfred. This would force the ore transports to travel through the open waters of the North Sea, where the Royal Navy could intercept them. Churchill assumed that Wilfred would provoke a German response and that the Allies would then implement Plan R 4 and occupy Norway. Though later implemented, Operation Wilfred was initially rejected by Neville Chamberlain and Lord Halifax for fear of an adverse reaction among neutral nations such as the United States.
The start of the Winter War between the Soviet Union and Finland in November 1939 changed the strategic situation, so in December 1939, the United Kingdom and France began serious planning for occupying northern Norway and Sweden under the guise of sending aid to Finland. Their plan called for a force to land in Narvik, in northern Norway, the main port for Swedish iron ore exports and then to take control of the Iron Ore Line railway between Narvik and Luleå in Sweden on the shore of the Gulf of Bothnia. This would also allow Allied forces to occupy the Swedish iron mines in Lapland. The plan received the support of both Chamberlain and Halifax. They were counting on the co-operation of Norway, which would alleviate some of the legal issues, but stern warnings issued to both Norway and Sweden by Germany resulted in strongly negative reactions in both countries. Planning for the expedition continued, but the justification for it was removed after the Moscow Peace Treaty between Finland and the Soviet Union had been signed in March 1940 and ended the Winter War.
Planning
Following a meeting with Vidkun Quisling from Norway on 14 December, 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 to begin preliminary planning for an invasion of Norway. The preliminary plan was named Studie Nord and called for only one division of German troops to carry out the invasion.
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 Allied 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. The new plan called for a full army corps, including a mountain division, an airborne division, a motorised 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 fallschirmjägers (paratroops) 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 motorised brigade. The entire operation would be supported by the X Air Corps, which consisted of some 1,000 aircraft of various types.
Preliminaries
In February, the Royal Navy destroyer HMS Cossack boarded the German tanker Altmark in Norwegian waters. The crew of Cossack overpowered the tanker's crew and rescued British prisoners of war onboard the ship, whose presence Norwegian authorities had repeatedly ignored. Both the attack and the transportation of prisoners of war into Norwegian waters by Altmark violated Norway's neutrality. Hitler regarded the incident as a clear sign that the Allies were also willing to violate Norwegian neutrality, which made him become even more strongly committed to invading Norway.
On 12 March, the British decided to send an expeditionary force to Norway just as the Winter War was winding down. The force began boarding on 13 March, but it was recalled and the operation cancelled because of the end of the Winter War. Instead, the Chamberlain war ministry voted to proceed with the mining operation in Norwegian waters, followed by troop landings.
On 5 April 1940, the long-planned Operation Wilfred was put into action, and a Royal Navy squadron led by the battlecruiser HMS Renown left Scapa Flow to mine Norwegian waters. The first German ships set sail for the invasion on 7 April 1940 at 3:00 a.m. 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 sunk by Kriegsmarine 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.
Invasion of Denmark
Strategically, Denmark's importance to Germany was as a staging area for operations in Norway. Considering its status as a minor nation bordering Germany, it was also seen as a country that would have to fall at some point. Given Denmark's position on the Baltic Sea, the country was also crucial for the control of naval and shipping access to major German and Soviet harbours.
At 04:00 on 9 April 1940, the German ambassador to Denmark, Cecil von Renthe-Fink, called the Danish Foreign Minister Peter Munch and requested a meeting with him. When the two men met 20 minutes later, Renthe-Fink declared that German troops were then moving in to occupy Denmark to protect the country from Anglo-French attacks. The German ambassador demanded that Danish resistance cease immediately and that contact be made between Danish authorities and the German armed forces. If the demands were not met, the Luftwaffe would bomb the capital, Copenhagen.
As the German demands were communicated, the first German advances had already been made, with forces landing on a regular commercial ferry in Gedser at 03:55 and moving north. German Fallschirmjäger (paratrooper) units had made unopposed landings and taken two airfields at Aalborg, the Storstrøm Bridge as well as the fortress of Masnedø, the latter being the first recorded attack in the world made by paratroopers.
At 04:20 local time, a reinforced battalion of German infantrymen from the 308th Regiment landed in Copenhagen harbour from the minelayer Hansestadt Danzig, quickly capturing the Danish garrison at the Citadel without encountering resistance. From the harbour, the Germans moved toward Amalienborg Palace to capture the Danish royal family. By the time the invasion forces arrived at the king's residence, the King's Royal Guard had been alerted and other reinforcements were on their way to the palace. The first German attack on Amalienborg was repulsed, giving Christian X and his ministers time to confer with the Danish Army chief General Prior. As the discussions were ongoing, several formations of Heinkel He 111 and Dornier Do 17 bombers roared over the city dropping leaflets headed, in Danish, OPROP! (proclamation).
At 05:25, two squadrons of German Messerschmitt Bf 110s attacked Værløse airfield on Zealand and neutralised the Danish Army Air Service by strafing. Despite Danish anti-aircraft fire, the German fighters destroyed ten Danish aircraft and seriously damaged another fourteen, thereby wiping out half of the entire Army Air Service.
Faced with the explicit threat of the Luftwaffe bombing the civilian population of Copenhagen, and with only General Prior in favour of fighting on, King Christian and the entire Danish government capitulated at approximately 06:00, in exchange for retaining political independence in domestic matters.
The invasion of Denmark lasted less than six hours and was the shortest military campaign conducted by the Germans during the war. The rapid Danish capitulation resulted in the uniquely-lenient occupation of Denmark, particularly until the summer of 1943, and in postponing the arrest and deportation of Danish Jews until nearly all of them were warned and on their way to refuge in neutral Sweden. In the end, 477 Danish Jews were deported, and 70 of them lost their lives, out of a pre-war total of Jews and half-Jews at a little over 8,000.
Invasion of Norway
Order of battle
The military headquarters of the operation was in Hotel Esplanade in Hamburg, where orders were given to, among others, the air units involved in the invasion. 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. 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 (General Nikolaus von Falkenhorst) and consisted of the following main units:
The initial invasion force was transported in several groups by the Kriegsmarine