Loading guns for Stavanger onboard Mendoza in Stettin. (Author’s collection)
Transport group ‘Karl’ leaving Stettin in the afternoon of 6 April heading for Kristiansand. Photo is taken from Kreta with Westsee, August Leonhardt and Wiegand following. (Author’s collection)
In the morning of 7 April a further eleven ships left Gotenhafen, scheduled to arrive in Oslo in the days following the invasion with further provisions and soldiers of the 196th ID. None of the vessels except Jan Wellem were to enter Norwegian ports prior to Weserday. The transport ships were a constant source of worry for the SKL. Security was not properly maintained during their loading and any incident they might become involved in at sea could potentially compromise the operation. Originally, the ships were to carry equipment and provisions with a minimum of troops onboard. During the last few days before departure, however, to the surprise of the navy, a large number of soldiers arrived to be transported to the invasion ports on orders from Group XXI.
On the evening of the 7th, Kontreadmiral Carsten Tank-Nielsen, commander of SDD2 in Bergen, called the Admiral Staff in Oslo, informing Chief of Staff Corneliussen that during the last few days an unusual number of German ships had entered the Leads south of Haugesund asking for pilots in Kopervik. German ships – in particular ore ships – were normal, but these were different. They had all been inspected, but most carried deck-loads of coal concealing the hatch-covers and the holds could not be accessed. The captains claimed to be heading for Murmansk, but what the coal should be used for there, nobody knew. Papers looked simplified or defective. No guns, ammunition or other military equipment had been found, but in the rooms inspected, the ships carried large amounts of food and supplies in crates marked Wehrmacht. In some cases captains and cargo-masters refused inspection of rooms, referring to ‘orders’. Tank-Nielsen found the activity suspicious and told the Chief of Staff he feared it might be an indication that the Germans ‘were up to something’. Corneliussen did not share his worries, but told him to ‘keep an eye on things’. Not very reassured, Tank-Nielsen ordered his officers to track the movements of the German ships and observe ‘increased preparedness until further notice’. It was left to each captain to interpret what this meant.
Bärenfels and Main were among the last ships of the first wave to arrive at Kopervik on 6 April asking for clearance and a pilot. By now, there were no pilots left and they had to wait, against the protests of their captains. The tankers Skagerrak and Kattegat for Trondheim and Narvik respectively, were also delayed and it seemed unlikely they would be in place in time to refuel the destroyers, causing deep concern in Group West. On 6 April, Naval Attaché Schreiber paid a visit to the Admiral Staff, complaining about recent delays to German merchant ships caused by extensive inspections. They were all in perfect order, he claimed, and there was no reason not to let them pass, but he offered no explanation as to why they were in such a hurry. Kontreadmiral Tank-Nielsen was not informed of Schreiber’s visit and it seems nobody in Oslo drew any conclusions worth mentioning.23
Befehlshaber der Unterseeboote (Commader of the Submarine Fleet), Konteradmiral Karl Dönitz had forty-eight U-boats in commission in April 1940; nine less than on the day hostilities commenced. During the first week of March, most U-boats had been withdrawn from the Atlantic. As soon as service, replenishment and rest for the crews had been completed, they were sent into the North Sea with orders to observe absolute radio silence and attack only warships or obvious troop convoys. Few results were obtained and four of the boats were lost, including the grounded U21. At the confirmation of Operation Weserübung on the 2nd, a total of thirty-two boats were at sea; fourteen Type VII and Type IX boats from Stadt and northwards and eighteen Type II boats in the Skagerrak and the North Sea. At 20:30 on the 6th, a signal from Dönitz to all U-boats contained the codeword ‘Hartmut’, indicating that sealed envelopes with orders written on water-soluble paper should be opened. The envelopes contained detailed orders for all boats to move into new positions along the Norwegian coast, taking care not to reveal their new positions. Allied warships and troop transports could still be attacked, but Norwegian or Danish ships should be left alone.24
From London, Vice Admiral (Submarines) Max Horton issued similar orders to his boats in the Skagerrak and Kattegat. German warships could be attacked but otherwise the boats should conceal their presence as much as possible. Merchant ships should be left alone – unless German warships and transports were encountered together, in which case it would be most important to attack the transports. Lieutenant Commander Bryant of Sealion found this order challenging and wrote in his diary on the 7th:
Some 25 merchant vessels were sighted during the day, mostly northbound. Some were suspicious, but none that I could say definitely were German transports . . . One small ship marked Estonia had a funnel corresponding to that of Saaberk Co of Hamburg. Five ships had no flags or markings, three being greyish. It was not possible to surface and investigate them so no action was taken. I was much concerned that I might be letting enemy ships by owing to taking no action. On the other hand, orders received conveyed the impression that it was essential not to compromise my position. The definition of a ‘transport’ was not clear in my mind.25
Due to improved signal discipline, German sigint had problems tracking the submarines compared to a few weeks earlier and was largely unaware of their number and whereabouts. Except for Trident, who had already stopped and examined several neutral merchant ships off Lista on the 4th and 5th, and Unity, who had made an unsuccessful attack on a U-boat in the Helgoland Bight on the 5th, there had been few indications of where the submarines were hiding. Based on the amount of land-based radio traffic, however, the B-Dienst estimated that some fifteen to twenty submarines were at sea.26 This number worried the SKL, as it might indicate that the Allies were aware of Operation Weserübung and preparing a trap. On the other hand, it might be that the large number of submarines was a defensive measure for their own operation against Norway, as in March. Either way, the submarine alert was heightened and preparation for increased air and sea protection of the transfer convoys was ordered.27
Hellmuth Guido Alexander Heye (1895–1970), captain of the heavy cruiser Admiral Hipper. (Author’s collection)
The 45-year-old Kapitän zur See Hellmuth Heye of the heavy cruiser Admiral Hipper was in charge of Kampfgruppe II, the warships for Trondheim. The 18,200-ton Hipper was the first of her class and extensive trials and modifications followed her entry into service a year earlier. Except for an uneventful sortie together with Scharnhorst and Gneisenau in February, Hipper had largely spent the winter in Wilhelmshaven until 20 March, when ordered to Cuxhaven in preparation for Weserübung. Also assigned to Group II were the destroyers of the 2nd Destroyer Flotilla: Paul Jacobi, Theodor Riedel, Bruno Heinemann and Friedrich Eckholdt under the command of Fregattenkapitän Rudolf von Pufendorf onboard Jacobi.28 Heye wrote:
I was, as the other group commanders, well aware of the magnitude of the task and the risk for the Kriegsmarine associated with this mission. In order to maintain security, it would be difficult to obtain intelligence and thus ample opportunities to end up in an unexpected situation, such as encountering the enemy at the start of the operation, running into a parallel enemy operation at the target, weather complications, missing resupplies etc. I compiled my considerations in an order for the ships of Group II . . . so that if something unexpected should happen, it would be possible to initiate swift countermeasures without long orders . . . The targets were ranked according to their priority, and the captains made aware of their priorities.29
During the afternoon of 6 April, the embarkation of soldiers commenced under the supervision of Hipper’s first officer, Korvettenkapitän