Operation Tannenbaum

Operation Tannenbaum (English: Operation Fir Tree or Christmas Tree), known earlier as Operation Green, was a planned but cancelled invasion of Switzerland by Nazi Germany during World War II.

Background
Even before the outbreak of war, Switzerland had every reason to expect invasion. After Adolf Hitler came to power in 1933, he made overtures towards the various National Socialist-leaning organizations in German-speaking countries, particularly Austria and Switzerland.

For tactical reasons Hitler made repeated assurances before the outbreak of the Second World War that Germany would respect Swiss neutrality in the event of a military conflict in Europe. In February 1937 he announced that "at all times, whatever happens, we will respect the inviolability and neutrality of Switzerland" to the Swiss federal councillor Edmund Schulthess, reiterating this promise shortly before the German invasion of Poland. These were, however, purely political maneuvers intended to guarantee Switzerland's passiveness. Nazi Germany planned to dispose of that country's independence after it had defeated its main enemies on the continent first.

Nazi attitudes towards Switzerland
In a meeting held with Fascist Italy's leader Benito Mussolini and Galeazzo Ciano (the Foreign Minister of Italy) in June 1941 Hitler stated his opinion on Switzerland quite plainly:

"'Switzerland possessed the most disgusting and miserable people and political system. The Swiss were the mortal enemies of the new Germany.'"

In a later discussion the German Foreign Minister Joachim von Ribbentrop directly alluded to the possibility of carving up Switzerland between the two Axis powers:

"'On the Duce's query whether Switzerland, as a true anachronism, had any future, the Reich Foreign Minister smiled and told the Duce that he would have to discuss this with the Führer.'"

In August 1942 Hitler further described Switzerland as "a pimple on the face of Europe" and as a state that no longer had a right to exist, denouncing the Swiss people as "a misbegotten branch of our Volk." Switzerland as a small, multilingual, decentralized democracy –  in which German-speakers felt an affinity with and loyalty towards their French-speaking fellow Swiss citizens, rather than towards their German "brothers" across the border  –  was from a National Socialist viewpoint a total antithesis of the racially homogeneous and collectivized "Führer State". Hitler also believed that the independent Swiss state had come to existence due to the temporary weakness of the Holy Roman Empire, and now that its power had been re-established after the National Socialist takeover, the country had become obsolete.

Much as Hitler despised the democratically-minded German Swiss as the "wayward branch of the German people", he still acknowledged their status as Germans. Furthermore, the openly pan-German political aims of the NSDAP called for the unification of all Germans into a Greater Germany, including the Swiss people. The first goal of the 25-point National Socialist Program stated that "We [the National Socialist Party] demand the unification of all Germans in the Greater Germany on the basis of the people's right to self-determination."

In their maps of Greater Germany, German textbooks included the Netherlands, Belgium, Austria, Bohemia-Moravia, the German-speaking parts of Switzerland, and western Poland from Danzig (now Gdańsk) to Kraków. Ignoring Switzerland's status as a sovereign state, these maps frequently showed its territory as a German Gau. The author of one of these textbooks, Ewald Banse, explained, "Quite naturally we count you Swiss as offshoots of the German nation, along with the Dutch, the Flemings, the Lorrainers, the Alsatians, the Austrians and the Bohemians... One day we will group ourselves around a single banner, and whosoever shall wish to separate us, we will exterminate!" Various Nazis were vocal about the German intent to "expand Germany's boundaries to the farthest limits of the old Holy Roman Empire, and even beyond."

Though not ideologically or politically aligned with the Nazis himself even if he offered them intellectual support, geopolitician Karl Haushofer had also advocated for the partition of Switzerland between its surrounding countries in his work, where Romandy (Welschland) would be awarded to Vichy France, Ticino to Italy, and Central and Eastern Switzerland to Germany.

Military preparations
An increase in Swiss defense spending was approved, with a first installment of 15 million Swiss francs (out of a total multiyear budget of 100 million francs) to go towards modernization. With Hitler’s renunciation of the Treaty of Versailles in 1935, this spending jumped up to 90 million francs. The K31 became the standard-issue infantry rifle in 1933, and was superior to the German Kar98 in ease of use, accuracy, and weight. By the end of World War II, nearly 350,000 would be produced.

Switzerland has a unique form of generalship. In peacetime, there is no officer with a rank higher than that of Korpskommandant (3-star-general). However, in times of war and in 'need', the Bundesversammlung elects a General to command the army and air force. On 30 August 1939, Henri Guisan was elected with 204 votes out of 227 cast. He immediately took charge of the situation.

The invasion of Poland by the Wehrmacht two days later caused the United Kingdom to declare war on Germany. Guisan called a general mobilization, and issued Operationsbefehl Nr. 1, the first of what was to be a series of evolving defensive plans. The first assigned the existing three army corps to the east, north, and west, with reserves in the center and south of the country. Guisan reported to the Federal Council on September 7 that by the moment of the British declaration of war, "our entire army had been in its operational positions for ten minutes." He also had his Chief of the General Staff increase the service eligibility age from 48 to 60 years old (men of these ages would form the rear-echelon Landsturm units), and ordered the formation of an entirely new army corps of 100,000 men.

Germany started planning the invasion of Switzerland on 25 June 1940, the day France surrendered. At this point the German Army in France consisted of three army groups with two million soldiers in 102 divisions. Switzerland and Liechtenstein were completely surrounded by Occupied France and the Axis Powers, and so Guisan issued Operationsbefehl Nr. 10, a complete overhaul of existing Swiss defensive plans. The St. Maurice and St. Gotthard Passes in the south and the Fortress Sargans in the northeast would serve as the defense line. The Alps would be their fortress. The Swiss 2nd, 3rd, and 4th Army Corps were to fight delaying actions at the border, while all who could retreated to the Alpine refuge known as the Réduit national. The population centres were, however, all located in the flat plains of the north. They would have to be left to the Germans in order for the rest to survive.

Hitler demanded to see plans for the invasion of Switzerland. Franz Halder, the head of OKH, recalled: "I was constantly hearing of outbursts of Hitler’s fury against Switzerland, which, given his mentality, might have led at any minute to military activities for the army." Captain Otto-Wilhelm Kurt von Menges in OKH submitted a draft plan for the invasion. Generaloberst Wilhelm Ritter von Leeb's Heeresgruppe ‘C’ (HGr. C), led by Generalleutnant Wilhelm List and 12th Army would conduct the attack. Leeb himself personally reconnoitered the terrain, studying the most promising invasion routes and paths of least resistance. Menges noted, in his plan, that Swiss resistance was unlikely and that a nonviolent Anschluss was the most likely result. With "the current political situation in Switzerland," he wrote, "it might accede to ultimatum demands in a peaceful manner, so that after a warlike border crossing a rapid transition to a peaceful invasion must be assured."

The plan continued to undergo revision until October, when 12th Army submitted its fourth draft, now called Operation Tannenbaum. The original plan called for 21 German divisions, but that figure was revised downwards to 11 by OKH. Halder himself had studied the border areas, and concluded that the "Jura frontier offers no favorable base for an attack. Switzerland rises, in successive waves of wood-covered terrain across the axis of an attack. The crossing points on the river Doubs and the border are few; the Swiss frontier position is strong." He decided on an infantry feint in the Jura in order to draw out the Swiss Army and then cut it off in the rear, as had been done in France. With the 11 German divisions and roughly 15 more Italian divisions prepared to enter from the south, the Swiss were looking at an invasion by somewhere between 300,000 and 500,000 men.

Hitler never gave the go-ahead, for reasons still uncertain today. Although the Wehrmacht feigned moves toward Switzerland in its offensives, it never attempted to invade. After D-Day, the operation was put on hold, and Switzerland remained neutral for the duration of the war.

German plans for Nazi rule in Switzerland
The German political objective in the expected conquest of Switzerland was to regain the bulk of the "racially suitable" Swiss population for Germandom, and aimed at direct annexation into the German Reich of at least its ethnic German parts.

With this purpose in mind Heinrich Himmler discussed the suitability of various people for the position of Reichskommissar for the 're-union' of Switzerland with Germany and its subsequent Reichsstatthalter with his subordinate Gottlob Berger in September 1941. This yet-to-be-chosen official would have had the task of facilitating the total amalgamation (Zusammenwachsen) of the Swiss and German populations. Himmler further attempted to expand the SS into Switzerland, with the formation of the Germanische SS Schweiz in 1942.

A document named Aktion S (bearing the full letterhead Reichsführer-SS, SS-Hauptamt, Aktion S[chweiz]) was also found within the Himmler files. It detailed at length the planned process for the establishment of Nazi rule in Switzerland from its initial conquest by the Wehrmacht up to its complete consolidation as a German province. It is not known whether this prepared plan was endorsed by any high-level members of the German government.

After the Second Armistice at Compiègne in June 1940, the Reich Interior Ministry produced a memorandum on the annexation of a strip of eastern France from the mouth of the Somme to Lake Geneva, intended as a reserve for post-war German colonization. The planned dissection of Switzerland would have accorded with this new French-German border, effectively leaving the French-speaking region of Romandy to be also annexed into the Reich despite the linguistic difference.

Italian involvement
Germany's wartime ally Italy under the rule of Benito Mussolini desired the Italian-speaking areas of Switzerland as part of its irredentist claims in Europe, particularly the Swiss canton of Ticino. In a tour of the Italian alpine regions he announced to his entourage that "the New Europe…could not have more than four or five large states; the small ones [would] have no further raison d'être and [would] have to disappear".

The country's future in an Axis-dominated Europe was further discussed in a 1940 round-table conference between Italian foreign minister Galeazzo Ciano and German foreign minister Joachim von Ribbentrop, also attended by Hitler. Ciano proposed that in the event of Switzerland's dissolution, it should be divided along the central chain of the Western Alps, since Italy desired the areas to the south of this demarcation line as part of its own war-aims. This would have left Italy in control of Ticino, Valais, and Graubünden.