Adapted from Bachmann, Die Deutsche Seekriegführung in der Ostsee nach Ausschaltung der Polnischen Marine im Herbst 1939.
Following the Molotov–Ribbentrop Pact announced on 23 August, the Swedish government, at a request from the General Staff, called up the naval reserves, manning ships, staffs and signal units, and initiating patrols along the territorial boundary. This resulted in a number of confrontations between Swedish escorts and German patrols. In a few cases shots were fired. There were no casualties from these events, but six Swedish sailors were killed in December when a German cable-cutting device found drifting exploded when retrieved.5
To facilitate their own coastal traffic, Sweden unilaterally declared a 4-mile neutrality zone, accepted by neither Germany nor the Allies. At first, the German minefields were placed up to, but not across, the Swedish 4-mile limit. To keep Swedish ships clear of the minefields, several channels were regularly swept inside the territorial limit and marked with light buoys. Soon these channels were also used by neutral shipping to avoid German interception. Hence, a request was made by the SKL to the German Foreign Office on 15 September to notify Stockholm that the 4-mile territorial limit declared by Sweden could no longer be recognised, only the normal 3-mile zone. This would force most merchant ships outside Swedish waters at a number of places, making them accessible for German inspection. The Foreign Office was at first unwilling to abide and it created tension between the two departments until the Swedish government was finally notified on 30 October that the minefields would be extended towards the 3-mile limit. Protests from Stockholm were futile and, on 24 November, Swedish authorities yielded, informing German naval authorities that, as ‘a preliminary measure’, the Swedish Navy would ‘concentrate the defence of Swedish neutrality to a 3-mile zone along their coast’. This would trap most of the Swedish Navy inside the Baltic and expose all merchant traffic through the Belts to German control.6
Denmark declared responsibility for a 3-mile zone during the first week of September and laid its own minefields in the Belts, protecting the entrance to Copenhagen.7 A proposal from Admiral Carls of Marinegruppenkommando Ost to close the Belts completely through a huge minefield from Ebeltoft to Sjellands Odde with a single opening, easily controlled by a handful of guard ships, was rejected by the SKL as it would have had to include Danish waters to be effective. It was feared that the British would use such an infringement of Danish waters as an excuse to start dropping mines from aircraft in the eastern waterways.8
Commerce Warfare
As soon as the initial minefields had been laid and the Polish Navy defeated, the Kriegsmarine started preparations for control of the commercial traffic in the Baltic. Due to the priorities in the west, there were few ships available for this task, and a multitude of ships were used during the first months. The first mission commenced on 12 September, when the destroyer Richard Beitzen and the old torpedo boat T107 left Swinemünde, heading for the Kattegat. No results were achieved and both ships docked in Kiel two days later. It is interesting to note that Beitzen was assigned this task as she had only one engine working at the time and was not considered fully operational. Destroyers were prioritised for operations in the west and only deployed in the Baltic as an exception or on short missions.
Eventually, as ships became available, an extensive patrol system was set up to halt any traffic benefiting the Allies. Ore, timber, cellulose and various foods were going in large quantities from Russia, Finland, the Baltic states and Scandinavia to both Britain and France and were now deemed contraband according to international law. All neutral ships were to be stopped, searched and arrested if found to have contraband on board.9 During 1939, more than 400 ships were stopped and of these some 12 per cent were arrested and taken by a prize crew to Swinemünde, Gotenhaven or Pillau, to be assessed by a prize court.
The minelayers Kaiser, Königin Luise, Preussen and Tannenberg were used on these missions, supported by torpedo boats and auxiliaries. Most of the time they were deployed off the Swedish islands Öland and Gotland, east to latitude 20 and north to Åland. Two ships were usually in the area at any one time, each patrol lasting eight to fourteen days. Traffic was substantial, and hundreds of ships were searched during the autumn until the ice halted most of the traffic towards the end of the year. At the end of September, the SKL transferred Admiral Scheer to Gruppe Ost as reinforcement in the war on commerce. Due to the perceived submarine threat she remained largely in the Danzig Bay, though, as there were no escorts to spare. Later, with the minefields in the west completed, Grille, Hansestadt Danzig and Kaiser were also subordinated to the eastern command and deployed for commerce war.
Zerstörer Z20 Karl Galster intercepting the neutral Norwegian freighter MS Balzac in the Skagerrak in the autumn of 1939. (Author’s collection)
Korvettenkapitän Freiherr Theodor von Mauchenheim genannt von Bechtolsheim and his men on the bridge of Karl Galster enjoying themselves firing on drifting mines in the Skagerrak in the autumn 1939. (Author’s collection)
Contrary to initial German expectations, the results of the Baltic commerce war were rather meagre. The Polish ships had escaped, and for obvious reasons there were few British or French around.10 Of the merchant ships inspected, few carried contraband. On 29 and 30 September, for instance, of fifty-eight vessels inspected in the eastern Skagerrak by a group of seven destroyers under Konteradmiral Lütjens, only nine were sent to Kiel for further verification. Likewise, of nine merchantmen inspected in Swinemünde on 3 October, six were released the same day as only three carried goods considered contraband or had improper papers. Firstly, the list of contraband relevant for the Baltic was short – oil, coal, ore, cellulose, timber and foodstuffs. Secondly, the presence of the German warships quickly became known and merchant ships carrying banned goods chose different routes. Weather conditions also soon turned out to be a problem as it was difficult for the prize crews to get across for inspection in the rough seas.
To increase the efficiency of the operations, aircraft were added to the patrols; He59 floatplanes being particularly useful. When a merchant ship was sighted, a message bag would be dropped on the deck, instructing it to steer for a position where German inspection vessels would be waiting. In some cases, a burst of machine-gun fire underlined the instructions. In others, prize crews carried by the aircraft were rowed across in an inflatable dinghy if the sea permitted a safe landing.
From the end of October, poor weather alternating with periods of severe cold and ice reduced traffic noticeably in the Baltic. The Schlesien and Schleswig-Holstein had to be used as icebreakers to prevent it coming to a total halt.11 The ice also restricted the working-up of new ships and crews (the cruiser Blücher among them) but, as many of the Kriegsmarine’s ships were in need of overhaul or modernisations, the yards worked at capacity through the winter.12
Schlesien