Apparently work on the first attack plans against Switzerland started on 24. June even before the armistice was in force. The evidence where the order came from to do the planning is spotty since quite a few documents were lost during the war. The information available is based on the war diary of Army Group C (HGr C).
The "Case Switzerland" was certainly a nuisance, but the main focus in these days was on the great victory achieved. Hitler wasn't decided about how to proceed with Great Britain. On 24. June there was an "Advance Order" to HGr A and B on the "continuation of the war against Great Britain" and to HGr C (which had to cover the Western part of the Swiss border) on a "special task for which an order will be given".
The original plan was worked out at the OKH by Hauptmann Otto Wilhelm von Menges. There exist some notes for a presentation at the OKH by von Menges dated 25. June 1940.
On 28. June 1940 the Swiss case was discussed at a meeting of the HGr and AOK in Versailles. The chief of the Germans operations sections asked, that the 12 Army (AOK 12), which was to be moved to the Swiss border, "should assemble quickly.". At the same time he declared that "in this case the Führer had mentioned only, that an occupation could be possible under certain conditions.".
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The operational idea of the plan was
The German intelligence assumed (correctly, see Swiss operational order No 10), that the main body of the swiss army was concentrated in the North-West and that the Western border was weakly occupied. The main line of resistance (including the state of the fortifications) was correctly identified.
The plan asked for 9 divisions as attack force:
The plan doesn't describe any axis of advance in great detail. The "idée de maneuvre" was similar to the one in the second second plan. The main idea was to take Zurich, Bern and Lucerne as quick as possible with the mobile troops. With this move, the Germans wanted to cut off the retreat route of the Swiss army towards to Alps.
The scarce mountain divisions should be used for the breakthrough only if necessary. One motorized division should attack through Chamonix and reach the Southern Rhône valley behind the fortresses of St. Maurice.
One infantry division should have attacked through Konstanz. Paras would have been used to take Bern and to open the exits of the Jura mountains to the South.
The Southern part and the Grisons would have been left to the Italians.
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The outline of the tactics mentions the formation of mixed combat groups based on the German experiences in Norway. Such a combat group would have consisted of tanks, artillery guns, motorized troops with some mountain equipment added.
One interesting point, is that von Menges mentions the need for the improvement of the bad quality of the maps of Switzerland the Germans could lay their hand on.
Until 9. July significant forces were assembled in the border area of Switzerland. These forces remained in the area only for a few weeks (see the German unit timeline), but would have formed a good basis for a quick attack. AOK 12 consisted of 9 divisions:
The other main body of the Wehrmacht close to the Swiss border was the battle hardened Panzergruppe Guderian. It consisted of four panzer and two motorized divisions.
[Last Update 30.08.2010]