Operation Weserübung

Operation Weserübung was the German codename for Nazi Germany's assault on Denmark and Norway during World War II and the opening operation of the Norwegian Campaign. (The term means Weser Exercise or Operation Weser, the Weser being a German river.)

In the early morning of April 9, 1940 &mdash; Wesertag ("Weser Day") &mdash; Germany invaded Denmark and Norway, ostensibly as a preventive maneuver against a planned (and openly discussed) Franco-British occupation of both these countries; upon arrival envoys of the invading Germans informed both countries' governments that the Wehrmacht had come to "protect the countries' neutrality" against Franco-British aggression. Significant differences in geography, location and climate between the two countries made the actual invasions very dissimilar.

The invasion fleet's nominal landing time &mdash; Weserzeit ("Weser Hour") &mdash; was set to 05:15 AM German time, equivalent to 04:15 Norwegian time.

Political and military background
Starting in the spring of 1939, the British Admiralty began to view Scandinavia as a potential theatre of war in a future conflict with Germany. The British government was reluctant to engage in another land conflict on the continent that they believed would be a repeat of World War I. So they began considering a blockade strategy in an attempt to weaken Germany indirectly. German industry was heavily dependent on the import of iron ore from the northern Swedish mining district, and much of this ore during the winter months was shipped through the northern Norwegian port of Narvik. Control of the Norwegian coast would also serve to tighten a blockade against Germany.

In October 1939, the chief of the German Kriegsmarine, Grand Admiral Erich Raeder, discussed with Adolf Hitler the danger posed by eventual British bases in Norway and the possibility of Germany seizing these bases before the United Kingdom could. The navy argued that possession of Norway would allow control of the nearby seas and serve as a staging base for future submarine operations against the UK. But at this time, the other branches of the Wehrmacht were not interested, and Hitler had just issued a directive stating that the main effort would be a land offensive through the Low Countries.

Toward the end of November, Winston Churchill, as a new member of the British War Cabinet, proposed the mining of Norwegian waters. This would force the ore transports to travel through the open waters of the North Sea, where the Royal Navy could interdict them. This proposal was turned down by Neville Chamberlain and Lord Halifax, due to fear of an adverse reaction among neutral nations such as the United States. After the start of the Winter War between the Soviet Union and Finland in November had changed the diplomatic situation, Churchill again proposed his mining scheme but once more was denied.

In December, the UK and France began serious planning for sending aid to Finland. Their plan called for a force to land at Narvik in northern Norway, the main port for Swedish iron ore exports, and to take control of the Malmbanan railway line from Narvik to Luleå in Sweden on the shore of the Gulf of Bothnia. Conveniently, this plan also would allow the allied forces to occupy the Swedish iron ore mining district. The plan received the support of both Chamberlain and Halifax. They were counting on the cooperation of Norway, which would alleviate some of the legal issues. But stern warnings issued to both Norway and Sweden resulted in strongly negative reactions in both countries. Planning for the expedition continued, but the justification for it was removed when Finland sued for peace in March 1940.

Planning
Convinced of the threat posed by the allies to the iron ore supply, Hitler ordered the German high command (OKW) to begin preliminary planning for an invasion of Norway on December 14, 1939. The preliminary plan was named Studie Nord and only called for one army division.

Between January 14 and 19 the Kriegsmarine developed an expanded version of this plan. They decided upon two key factors: that surprise was essential to reduce the threat of Norwegian resistance (and British intervention); the second to use the faster German warships, rather than comparatively slow merchant ships, as troop transports. This would allow all targets to be occupied simultaneously, as the transport ships only had limited range. This 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 this force were the following: The plan also called for the rapid capture of the kings of Denmark and Norway in the hopes that would trigger a rapid surrender.
 * The Norwegian capital Oslo and nearby population centers
 * Bergen
 * Narvik
 * Tromsø
 * Trondheim
 * Stavanger

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

The final plan was code-named Operation Weserübung ("Exercise on the Weser") on January 27, 1940. It would be under the command of the XXI Army Group and include the 3rd Mountain Division and five infantry divisions, none of the latter having yet been tested in battle. The initial echelon 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 send also the 2nd Mountain Division was made later.

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

Preliminaries
In February the British destroyer Cossack boarded the German transport ship Altmark while in Norwegian waters, thereby violating Norwegian neutrality, rescuing POWs held also in violation of Norwegian neutrality (the Altmark was obliged to release them as soon as she entered neutral territory). Hitler regarded this as a clear sign that the UK was willing to violate Norwegian neutrality, and so became even more strongly committed to the invasion.

On March 12, the UK decided to send an expeditionary force to Norway just as the Winter War was winding down. The expeditionary force began boarding on March 13, but it was recalled - and the operation cancelled - with 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 April 3, and on April 8 a British destroyer began laying the first mines in Norwegian waters. On April 9 the German invasion was under way.

Invasion of Denmark
Strategically, Denmark was relatively unimportant to Germany, except as a staging area for operations in Norway, and of course as a border nation to Germany which would have to be controlled in some way. The country is small and relatively flat, ideal territory for German army operations, and Denmark's small army had little hope of success in armed resistance. Nevertheless, in the early morning hours a few Danish troops engaged the German army, suffering a few dozen dead.

After 1,000 German infantry in the early morning landed in Copenhagen harbor, a detachment of troops from the King's royal guard began to engage them. Just as the first few shots were being fired, several formations of Heinkel 111 and Dornier 17 bombers roared over the city. Faced with the explicit threat of the Luftwaffe bombing the civilian population of Copenhagen, the Danish government capitulated in exchange for retaining political independence in domestic matters. This resulted in the uniquely lenient Occupation of Denmark, particularly until the summer of 1943, and also in postponing the arrest and deportation of Danish Jews until nearly all of them were warned and on their way to refuge in Sweden. In the end, fewer than 500 Danish Jews were deported, and 52 of them lost their lives, out of a pre-war total estimated at 8,000.

Though Denmark and the rest of Scandinavia (except for Norway) generally had little military significance, they had strategic, economic and ideological importance. As Dr. Werner Best, the second German plenipotentiary, said, "Denmark provided significant economic assistance through its agriculture. It was also an important link to Sweden."

Motivation and Order of Battle
Main article: Operation Weserübung Order of Battle

Norway was important to Germany for two primary reasons: as a base for naval units, including U-boats, to harass 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 in order 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 percent of which originated from Narvik.

The invasion of Norway was given to the Army Corps XXI under General Nikolaus von Falkenhorst and consisted of the following main units:
 * 163rd Infantry Division
 * 69th Infantry Division
 * 169th Infantry Division
 * 181st Infantry Division
 * 214th Infantry Division
 * two regiments of the 3rd Mountain Division

The initial invasion force was transported in several groups by ships of the Kriegsmarine:
 * 1) Battlecruisers (or fast battleships) Scharnhorst and Gneisenau as distant cover, plus 10 destroyers with 2,000 mountaineering troops under General Eduard Dietl to Narvik;
 * 2) Heavy cruiser Admiral Hipper and 4 destroyers with 1,700 troops to Trondheim;
 * 3) Light cruisers Köln and Königsberg, artillery training ship Bremse, transport Karl Peters, 2 torpedo boats and 5 motor torpedo boats with 1,900 troops to Bergen;
 * 4) Light cruiser Karlsruhe, 3 torpedo boats, 7 motor torpedo boats with 1,100 troops to Kristiansand;
 * 5) Heavy cruiser Blücher, heavy cruiser (formerly pocket battleship) Lützow, light cruiser Emden, 3 torpedo boats and 8 minesweepers with 2,000 troops to Oslo;
 * 6) 4 minesweepers with 150 troops to Egersund.

Concise timeline

 * Late in the evening of April 8, 1940, Kampfgruppe 5 was spotted by the Norwegian guard vessel Pol III. Pol III was defeated, her captain the first Norwegian military casualty during the war.
 * In an act of irony, the German heavy cruiser Blücher was sunk in the Oslofjord April 9 by 48-year-old German Krupp guns (named Moses and Aron, of 280 mm calibre, installed at Oscarsborg Fortress in May 1893) and equally ancient torpedoes:
 * German ships sailed up the fjord leading to Oslo, reaching the Drøbak Narrows (Drøbaksundet). In the early morning of April 9, the gunners at Oscarsborg Fortress fired on the leading ship, the Blücher, which had been illuminated by spotlights at about 0515hrs. Within two hours, the ship, unable to maneuver in the narrow fjord, was sunk with about 600-1,000 men. The now obvious threat from the fortress delayed the rest of the naval invasion group long enough for the Royal family and Parliament to be evacuated, along with the national treasury. As a result, Norway never surrendered to the Germans, leaving the Quisling government illegitimate and permitting Norway to participate as an Ally in the war, rather than as a conquered nation.
 * German airborne troops landed at Oslo airport Fornebu, Kristiansand airport Kjevik, and Sola Air Station &mdash; the latter constituting the first paratrooper (Fallschirmjäger) attack in history; coincidentally, among the Luftwaffe pilots landing at Kjevik was Reinhard Heydrich. [[Image:Karte Oscarsborg.png|right|150px|thumb|Map of Oslo fjord with Oscarsborg]]
 * Quisling's radio-effected coup d'etat &mdash; another first.
 * Partly thanks to the sinking of the Blücher in the Oslo Fjord narrows, the Royal family and Parliament (including government) evaded the German invasion force; King Haakon refused to lay down arms; Clash at Midtskogen; bombs at Elverum and Nybergsund; Royal family, Parliament, and national gold reserves moved northward ahead of the Germans.
 * Cities/towns Bergen, Stavanger, Egersund, Kristiansand S, Arendal, Horten, Trondheim and Narvik attacked and occupied within 24 hours.
 * Heroic, but wholly ineffective, stand by the Norwegian armored coastal defence ships Norge and Eidsvold at Narvik. Both ships torpedoed and sunk with great loss of life.
 * First and Second Naval Battle of Narvik (Royal Navy vs Kriegsmarine).
 * The German force took Narvik and landed the 2,000 mountain infantry, but a British naval counterattack by the old battleship HMS Warspite and a flotilla of destroyers over several days succeeded in sinking all 10 German destroyers once they ran out of fuel and ammunition.
 * Devastating bombing of towns Åndalsnes, Molde, Kristiansund N, Steinkjer, Namsos, Bodø, Narvik &mdash; some of them tactically bombed, some terror-bombed.
 * Main German land campaign northward from Oslo with superior equipment; Norwegian soldiers with turn-of-the-century weapons, along with some British and French troops (see Namsos Campaign), stop invaders for a time before yielding &mdash; first land combat action between British Army and Wehrmacht in WWII.
 * Land battles at Narvik: Norwegian and Allied (French, Polish) forces under General Carl Gustav Fleischer achieve the &mdash; first tactical victory against the Wehrmacht in WWII &mdash; and the following unfortunate withdrawal of the Allied forces (mentioned below); Fighting at Gratangen.
 * With the evacuation of the King and the Parliament from Molde to Tromsø on April 29, and the allied evacuation of Åndalsnes on May 1, resistance in Southern Norway comes to an end.
 * The "last stand": Hegra Fortress (Fort Ingstadkleiven) resisted the siege until May 5 -- of Allied propaganda importance, like Narvik.
 * King Haakon, Crown Prince Olav, and parliament left from Tromsø 7 June (aboard British cruiser HMS Devonshire, bound for UK) to represent Norway in exile (King returned to Oslo exact same 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.
 * Norway capitulated (though Norwegian armed forces continued fighting the Germans abroad and at home until the German capitulation on May 8, 1945) on June 10, 1940, two months after Wesertag, this made Norway the conquered country which had withstood a German invasion for the longest time before succumbing.

In the far north, Norwegian, French and Polish troops, supported by the Royal Navy and the RAF, fought against the Germans over the control of the Norwegian harbour Narvik, important for the year-round export of Swedish iron ore (The Swedish harbour of Luleå is blocked by ice in the winter months). The Germans were driven out of Narvik on May 28, but due to the deteriorating situation on the European continent, the allied troops were withdrawn in Operation Alphabet &mdash; and the Germans recaptured Narvik on June 9, by then deserted also by the civilians due to massive Luftwaffe bombing.

The Encircling of Sweden and Finland
Operation Weserübung did not include a military assault on (likewise neutral) Sweden &mdash; there was no need. By holding Norway, the Danish straits and most of the shores of the Baltic Sea, the Third Reich encircled Sweden from the north, west and south &mdash; and in the East, there was the Soviet Union, the successor of Sweden's and Finland's arch-enemy Russia, on friendly terms with Hitler under the terms of the Molotov-Ribbentrop Pact. A small number of Finnish volunteers helped the Norwegian army against Germans in an ambulance unit.

Sweden's and Finland's trade was totally controlled by the Kriegsmarine. As a consequence, Germany put pressure on neutral Sweden to permit transit of military goods and soldiers on leave. On June 18, 1940, an agreement was reached. Soldiers were to travel unarmed and not be part of unit movements. A total of 2.14 million German soldiers, and more than 100,000 German military railway carriages, crossed Sweden until this traffic was officially suspended on August 20, 1943.

In August 1940, Finland agreed to grant access to its territory for the Wehrmacht. Initially for transit of troops and military equipment to and from northernmost Norway, but soon also for minor bases along the transit road that eventually would grow in the preparation for Operation Barbarossa.