By Prof. Mauno Jokipii, Jatkosodan synty [The Birth of the Continuation War] (Otava 1987, ISBN 951-1-08799-1), p. 108-113:
2. The occupation of Norway in spring 1940 Changes the position of Finland
The background of the German occupation of Norway had mainly to do with naval strategy. The experiences of the First World War as well as more recent war games showed that with its mighty navy and great mine blockades, Britain could close the German navy within the North Sea, unless Germany could get bases from farther away for operations on the North Atlantic. Grand Admiral Raeder is known to have hoped for a naval base for Germany from Mid or Northern Norway already in 1937. The Pact of 1939 with the USSR only gave a small submarine base, "Basis Nord", from the Litsa Bay to the east from Petsamo, but the service there from ships or the unbuilt shores of the desolate tundra remained small in scale and insufficient for the needs. Therefore, in the German naval circles Operation Weserübung began to take shape from November 1939 on, a plan of conquering Norway with a naval surprise attack, to get bases from there to extend the trade war to the Atlantic, against the vital sea communications of Britain. Also securing the transport of ore from Narvik motivated the German operation, although only a minor share of the Swedish ore exports to Germany used this route. It may be that for Hitler, the latter issue was more important than the need of naval bases, and that rumors of the British triggered the action.
Operation Weserübung targeted against Norway did not commence until later in the spring on 9 April 1940, which is after the Finnish Winter War had already ended. Also Britain was preparing for a respective operation, and thus Germany only made it somewhat earlier.
Both sides were active at the same time. The decision of the British Government to mine the coastal seaways of the neutral Norway was made on 1 April, France approved it on 5 April, and the minelayers that set out immediately began their work on the Norwegian seaways on 8 April. -- Hitler's decision to execute the German operation was made on 2 April, the slowest cargo ships meant to reach farthest set out on the sea on 3 April, and the large and fast units of the war fleet on 7 April, which is on the same day as the British Home Fleet, which they were close to encounter on the western side of Trondheim on 8 April. When the German landing all along the Norwegian coastline took place at the same time on 9 April, they could thus use as a formal reason the mining carried out by the Royal Navy on the previous day.
In Southern Norway the German operations made quick progress, but Narvik fell to the Germans only after difficult battles in early June. During the battles, Finnmark in Northern Norway was planned as a neutral area under Swedish military control, but after the German victory this did not materialize. The North was for a while ruled by a pro-German satellite government of Norway that had been established in Oslo, but as soon as 15 June Hitler ordered also the Northern Finnmark to be occupied by light German troops.
The development of the [Finnish] foreign policy after the Winter War made the German Envoy to Helsinki, Mr Blücher, afraid for some time that until now neutral Finland would pick the side of the Allied in the great power war in order to secure its position. From a high Finnish authority he got to know on 5 April that the British operation to Narvik would begin within three days. The talks of Foreign Minister Witting on 6 April seemed to point towards a change of Finnish policy line. The moving about in Helsinki of Mr Bell, the former Consul General of Britain of the years 1918-19, for propaganda missions made Mr Blücher nervous, as well as the very cordial reception by [the Prime Minister, Mr Risto] Ryti of Mr Charles Hambro, the under secretary of the British Ministry of Economic Warfare (MEW) on 7 April 1940. Because of the cold relations with Germany, Finland might try to make arrangements of its trade via the Arctic Ocean with the support of Britain.
When the German attack on Norway had begun on 9 April 1940, Blücher's fear of a Finnish change of policy still continued. Among others, he wrote to the Auswärtiges Amt about this possibility on 19 April. Obviously the Finnish Government has indeed considered closer relations to the West. However, when the trade with Central Europe would have then been entirely cut off because of Germany, economically it would have been change for the worse. Speculations of a larger volume of trade with the West seem to have ended in Finland, when Britain notified Ryti on 18 April 1940 about finishing all trade with Scandinavia for the duration of the war in Norway. The relatively quick turning of Finland (already on 26 April) was also caused to a great deal by the fact that only with German permission could the shipments of the orders of war material from the time of the Winter War -- regarded as having primary importance to the Finnish capability for defense, now stuck in Norwegian harbors -- be released and get delivered.
The battle of Narvik lasted from April 1940 to early June. The hard-pressed German troops of General Dietl (most of 3rd Mountain Division and naval forces) were saved by the voluntary departure of the superior British forces on 4-8 June 1940, due to the situation on the Western front. All of Norway surrendered to Germany on the next day. The 2nd Mountain Division, advancing from the south by road, was still 130 km from Narvik then, but after a march across the mountains (Operation Buffel) it arrived there on 13 June. In mid-June, the remaining 3rd Mountain Division was brought by ships to Narvik and further to Tromsø, which is close to the border of the Finnish western "arm". From here on, the neighbor of Finland in the North was not the small, neutral Norway, but the strong Great-German Reich.
From the papers of the V Army Corps, commanded by General Siilasvuo from Oulu and covering the whole Northern Finland, one can well track how accurately the Finns knew about these issues. The General HQ informed on 30 May, how a large British aircraft had visited Kirkenes on 23 May, with its Norwegian defense being taken in Narvik direction. The British large naval forces moving in the waters of this area were listed. The British had held the opinion that "the Russians will not take measures regarding Northern Norway" (underlined in the source).
In the evening of 8 June, two Norwegian aircraft landed on Salmijärvi of Petsamo, and later (on 9 June) another two, of which one was a bomber, with a total of 40 men in them. In the morning of 9 June, two Norwegian aircraft landed at Petsamo, and still one more in the evening. The airmen told that Norway had made an armistice, and the Allied troops are departing from Norway. The Norwegians requested to be interned. They also told it was feared that Soviet troops will land in Northern Norway. At Salmijärvi, also 30 Norwegian civilians had crossed the border, as well as the Consuls of Britain, Belgium, and Spain.
The General HQ telegraphed to the 11th Division at Rovaniemi on 9 June 1940: "Norwegians who have crossed the border will be interned, separating officers, NCO's, staff, and civilians. Must be treated well, to be transferred to Rovaniemi at the first instance. The Air Force will send Finnish pilots to fetch the Norwegian aircraft. By order, Colonel Melander."
A couple of days later refugees are listed: from Enontekiö 40, Utsjoki 38, Salmijärvi 13, and Kolttaköngäs 3. The Assistant Chief of the State Police, Bruno Aaltonen, had arrived at Rovaniemi to lead the internment. -- By 13 June, already more than 200 refugees had arrived at Siilastupa, among them Air Force officers, and at Nuorgam, first 44 soldiers and 4 civilians, then 21 soldiers more. "According to what the Norwegians told, a deal would have been made with the Germans, according to which the Military Province of Tromsø would remain under Norwegian control, where they could carry weapons and hold exercises. The Norwegians are however said to have requested the Germans to occupy some locations also in this area".
For the interned Norwegian military persons, the Civil Guard was ordered to establish a camp in Kemi on 15 June 1940, where all of them were to be reported and sent.
Even though after the German victory Northern Norway initially remained practically Norwegian land, small German garrisons were sent to its towns as symbols of the formal taking of power. Thus the German flag was hoisted in the flagpole at Kirkenes on 15 June 1940 by the SS-police troops (Sonder-Bataillon "Reitz") that had been brought on the spot. On the following day, the town was visited with a German aircraft by the State Commissar Terboven and about ten authorities of the new administration to negotiate with the "Royal" Norwegian authorities on the new situation. As it is known, Terboven, who was still running the administration aside from the Quisling "regime", overtook the latter by the autumn and from 27 September 1940 onwards ruled Norway as a kind of German Governor General.
The Finnish General HQ informed its troops in Northern Finland on 1 July that about 30 German infantry soldiers carried out guard duty in Kirkenes then, brought by air. The harbor was guarded instead by Norwegian soldiers. According to Norwegian information, in the near future about 2000 additional Germans were expected to arrive at Kirkenes, to guard the border. At least a part of them have soon arrived, as the Norwegian Captain Bengts had been at Svanvik by the Paatsjoki river to reconnoiter accommodation for about 40-50 Germans, who would arrive there as border guards. Bengts had told that the Germans had been very interested in the traffic to Liinahamari and the trade relations between Finnmark and Finland, which in their opinion should be quickly fixed. -- By the direct order of Himmler, the Commander of the SS-Battalion, Reitz, began already at the end of July tying direct relations with Finns. He is known to have met the military Commander of Northern Finland, General Siilasvuo, in Ivalo on 5 August 1940.
As it is seen from the previous, the Finns could follow quite accurately the events of Northern Norway with the help of their relations and refugees.
From the viewpoints of grand politics, economy, and strategy, even a weak occupation of Northern Norway had great significance for Finland. Even though the number of German troops in Finnmark was still small, they could be increased as needed. In Finland it was realized that the trickle of trade with the West, which had been just started via Petsamo, was entirely dependent on German approval. Even if during the Winter War, British aid could still have made it to Finland via the neutral Norway, it could no more manage via the occupied Norway and the Danish straits under German control. Besides that, Britain had been defeated for the moment both on the Continent and in Norway, and a landing was even threatening its domestic island.
As Finland needed for its policy a counterweight to the Soviet Union, Sweden and Germany were thus left as its only alternatives. When co-operation with the little Sweden had been cut off by the Soviet Union right after the Winter War as previously explained, only the direction of the victorious Germany was left open for Finland. The Finnish leading statesmen realized this, quite apart from their personal preferences. On 4 July, Foreign Minister Witting said to Blücher that there was an "avalanche-like" development in Finland for an attitude favorable for Germany. It went thus far that a Cabinet was even planned that would orient itself towards Berlin. However, the abrupt political turn of the Finns, with coats being turned by the wind, had such an obvious tendency that the official Germany did not want to visibly respond to it at once.
On 13 August 1940 Hitler ordered a great reinforcement of the German troops in Northern Norway. Then the 2nd Mountain Division, deployed to the north from Trondheim, had to be shipped to the Kirkenes area, and the 3rd Mountain Division had to transfer its troops by land northwards from Narvik, among others to the fjord of Alta, which later became a major base for the German open sea fleet. The German Mountain Divisions in Norway had been joined into a Mountain Army Corps in July 1940, under the lead of "the victor of Narvik", General Dietl. He was also assigned on 13 August the mission of preparing an operation known with the code name Renntier, with the purpose of rapidly taking the Petsamo region, including the Kolosjoki nickel mine and Liinahamari harbor, if the USSR should attack Finland. However, the second part of the mission was preventing possible landings in Northern Norway, planned by the Western Allies, or protecting the very long shoreline of Finnmark.
Because of the order, the Mountain Army Corps was deployed in August-September 1940 to its new northern guard posts and also its winter camp to be as follows:
2nd Mountain Division to Finnmark county
Reinforced Mountain Jaeger Regiment 136 from Kirkenes to Teno (Tana) river
Reinforced Mountain Jaeger Regiment 137 from Hammerfest to Lakselv and Karasjok and from Alta to Kautokeino
3rd Mountain Division to Nordland county
Reinforced Mountain Jaeger Regiment 138 from Tromsø to Nordreisa and Balsfjord
Reinforced Mountain Jaeger Regiment 139 from Narvik to Saetermoen
Troops subdued to the Army Corps in the middle of the region in Alta fjord;
the HQ there aboard a passenger ship
The before mentioned SS-battalion Reitz took responsibility from here on of only guard duty of the Varanger Peninsula. It was assisted by another battalion after August 1940, and together they became on the order of SS-Führungshauptamt of 12 November 1940 the SS-Totenkopf-Standarte K or the SS-Police Regiment Kirkenes. In April 1941 it was renamed as SS-Infantry Regiment 9. The plan that was born as desk work in Berlin or Oslo deployed troops far inland. Thus the Mountain Army Corps achieved among others that in Kautokeino, instead of a battalion, only a company was stationed; even less would have sufficed at the border of the friendly Finland.
From Hitler's viewpoint, Dietl's troops were securing eastwards his extreme left flank by the Arctic Ocean, just like the training division sent to Romania and the Air Force secured his right flank by the Black Sea. At the same time, the German troops in Finnmark secured even from behind the border the Petsamo nickel for Germany for all eventualities, equally as the German troops in Romania secured with their presence the Romanian oil remaining available for the Greater Germany. From Finland's viewpoint, the reinforcement of German troops in Northern Norway showed why Germany requested right of transit there. Under the prevailing circumstances of the time, there was no reason to turn down Germany.