About World War 2: Operation Tannenbaum—The German Plan to Invade Switzerland

Updated on September 30, 2017
UnnamedHarald profile image

I try to make history readable and interesting, warts and all. We must look to the past to understand the present and confront the future.

Switzerland Surrounded

WW2: Switzerland (white) surrounded by territory controlled by the Axis Powers (blue) from 1940 to 1944.
WW2: Switzerland (white) surrounded by territory controlled by the Axis Powers (blue) from 1940 to 1944. | Source

Planning Begins

When World War Two broke out, Switzerland maintained its long-standing policy of neutrality (in effect since 1815) and received assurances from Germany that her neutrality would be respected. In fact, Hitler despised the Swiss, considering its ethnic Germans “degenerate” because of their democratic ways and a “wayward branch of the German People.” When France surrendered on June 25, 1940, the Germans started planning Operation Tannenbaum (“Christmas Tree”), the invasion of Switzerland.

Anti-Tank Defenses

WWII: Anti-tank obstacle, Birmensdorf ZH, Switzerland
WWII: Anti-tank obstacle, Birmensdorf ZH, Switzerland | Source

The Swiss Mobilize Early

Well before that, however, the Swiss had taken measures to defend themselves. They had witnessed the same assurances given to Poland and, when the Germans launched their Blitzkrieg against the Poles on September 1, 1939, began mobilizing their defenses. By the time the British declared war on Germany two days later on September 3, the three Swiss army corps had been deployed near the country's eastern, northern and western borders, with reserve troops placed in the central and southern regions. In addition, the service eligibility age was increased from 48 to 60 years in order to form a fourth army corps of 100,000 men. At its largest, the Swiss Army and its Landsturm units (militias) would number nearly 500,000 troops.

The National Redoubt Plan

When Switzerland found herself surrounded by Axis-controlled countries, including Vichy France and Italy, their initial plan of defense was overhauled. The regular Army corps were then to hold off any assaults from the north and south as long as they could until being forced back. At that point, they were to implement the National Redoubt Plan and join the rest of the army in the in the Alps, an extremely rugged and mountainous region stretching east to west across the country containing forts and fortresses. This meant that the most populous and industrial areas in the plains of the north of Switzerland would fall, but all the passes and tunnels through the Alps would be denied to the enemy, thereby making the invasion of Switzerland nearly pointless, given the casualties the invader's armies would incur.

Hidden Fortresses

Fort Airolo, built circa 1890. Part of the National Redoubt fortresses.
Fort Airolo, built circa 1890. Part of the National Redoubt fortresses. | Source

Operation Tannenbaum Evolves

Originally, Operation Tannenbaum had called for 21 German divisions for the invasion, but, in successive months, this was reduced to 11, with about 12 Italian divisions invading from the south, involving up to 500,000 Axis troops. It was hoped that an initial feint would draw out the Swiss Army from their National Redoubt so the Germans could then sweep around behind the main body and cut it off from the rear similar to the German invasion of France.

Swiss Terrain, Her Biggest Defense

Hitler Furious, Canaris Persuasive

Although the German Army made ominous advances toward the Swiss border, the order to invade never came. Operation Tannenbaum was kept ready until 1944, when it was finally canceled. It is still unclear, given Hitler's continued furious tirades against the Swiss, the exact reasons why. Undoubtedly, the cost in men and materiel was a major factor. Weighed against the annoying Swiss state of neutrality, the Germans probably decided that half a loaf was better than none-- they could do business with the Swiss even while the Allies did the same. But Hitler had ordered actions before based more on his hatred than logic (for example, his order to General Paulus to fight in Stalingrad to the last man). Was there another factor? It appears that Admiral Wilhelm Canaris, head of German Military Intelligence (Abwehr) and a fierce anti-Nazi, embellished Switzerland's capabilities and will to resist. This may have persuaded Hitler to accept the status quo of Switzerland's neutrality. Canaris' various anti-Nazi activities, once discovered, would result in his execution just days before the end of the war.

A Swiss Messerschmitt

WW2: Messerschmitt Bf 109 E-3 (Me 109) fighter aircraft as used by the Swiss Air Force, 1939-1948.
WW2: Messerschmitt Bf 109 E-3 (Me 109) fighter aircraft as used by the Swiss Air Force, 1939-1948. | Source

Swiss Cheese Airspace

Despite hanging on to her neutrality, Switzerland endured many incursions of her air space by both the Axis and the Allies. Early on, the Swiss air force shot down eleven German planes, while losing two, until the Germans threatened severe repercussions. The Swiss Air Force consisted mainly of about 90 Messerschmitt BF-109 fighters which they had bought from Germany. This only added to Hitler's fury. Deciding not to prod the beast, the Swiss stopped aerial combat, though they still used anti-aircraft guns when combatants overflew their territory. Later, when the Allies launched their bomber offensive, damaged aircraft would seek to land in Switzerland and their crews would be interned (by war's end, about 1,700 American airmen were held by the Swiss). As the bombing became more pronounced, Allied bombers sometimes accidentally strayed into Switzerland and bombed Swiss cities, including the largest city, Zurich. On some occasions the circumstances of the “accidents” were suspect, but, officially, the bombings were all put down to navigation errors. In the shadowy world of diplomacy, a few bombed factories doing business with the Third Reich were the price of neutrality. The last Swiss plane to be lost was shot down by by an American bomber.

German Town Tricked Bombers

After the Swiss complained about Americans accidentally bombing Swiss territory, the US was a lot more careful. The town of Konstanz, Germany, situated next to the Swiss border, took advantage of this and left its city lights on at nights. Bombers then thought it was a Swiss town and Konstanz was never bombed during World War Two.

Can You Spot the Hidden Gun Battery?

The Ermitage gun battery in the cliff-side. Part of the Swiss Scex Fortification in the National Redoubt.
The Ermitage gun battery in the cliff-side. Part of the Swiss Scex Fortification in the National Redoubt. | Source

Neutral Doesn't Mean Innocent

Playing a neutral nation in the midst of a world war is difficult at best. Belgium was neutral; Denmark was neutral; the Netherlands were neutral. They all fell within days of Germany violating their neutrality. The Swiss, by utilizing an “armed” neutrality, that is, physically preparing to defend itself, probably did stave off a German invasion. There were Nazi sympathizers in Switzerland, including the army, just like there were in Britain and the U.S. Many Swiss companies, in order to do business, dealt with the Axis. Being neutral, these companies had only their consciences to soothe, and many did. It should be noted that some Allied companies had to both soothe their consciences and circumvent the law to do business with the Germans. The Swiss turned back a lot of refugees from their border-- but they also allowed some in. There were plenty of shady Swiss dealings going on during the war, but no nation, Allied, Axis or neutral, came out of World War Two without blood on its hands.

In Switzerland's case, the fact that they remained neutral was not because they declared their neutrality, but because they were prepared to defend themselves against the world's best military machine of the time.

© 2012 David Hunt


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    • profile image


      2 years ago

      I'm probably a little off, but have an interesting concept. Look how the Nazis especially invaded what is now known as the Eastern Bloc. Was this really all built up and done to prevent a Russian invasion into Europe? As nasty as it was, wasn't World War 2 largely better than what might have otherwise happened?

      It certainly served a purpose for those that controlled Europe as a result, and rectified some old problems, as war does. Look now at the new line of war being cultivated in the same area for likely similar reasons, especially with Ukraine. Is what is now transpiring occurring to prevent a potential Russian invasion into Europe, while denying its likelihood?

    • UnnamedHarald profile imageAUTHOR

      David Hunt 

      3 years ago from Cedar Rapids, Iowa

      Thanks for commenting, Peter. Even today, the Swiss implement "armed neutrality". For example, bridges and tunnels in the Alps must be designed so they can be destroyed should an invader approach.

    • Peter Geekie profile image

      Peter Geekie 

      3 years ago from Sittingbourne

      Thank you for a well researched and written article about a subject I know little or nothing about. Nazi Germany soon learned they were not the all conquering power they thought they were.

      kind regards Peter

    • UnnamedHarald profile imageAUTHOR

      David Hunt 

      7 years ago from Cedar Rapids, Iowa

      Very interesting comment, jbreguet. The Swiss seemed determined to ensure that any invader would find it extremely unprofitable to violate their neutrality and had every intention of following through with laying waste to everything a conqueror might want. Thanks for stopping by.

    • profile image


      7 years ago

      My father was a Swiss industrialist during WWII. The Swiss government, in anticipation of a German invasion, ordered all factories to have a plan to disable each piece of machinery (run it without oil, destroy vital components, etc). Additionally, every tunnel, every overpass, every bridge was prepared for demolition.

    • UnnamedHarald profile imageAUTHOR

      David Hunt 

      8 years ago from Cedar Rapids, Iowa

      Thanks for sharing, phdast7. The more I research, the more I learn that being "neutral" is a very dicey proposition and a constant high-wire act of convincing ALL belligerents it's not in their best interest to invade. Declaring neutrality is the easy part.

    • phdast7 profile image

      Theresa Ast 

      8 years ago from Atlanta, Georgia

      Very informative and well-written as usual. I knew that Switzerland was neutral and that was about it! So this really is very helpful. Sharing,

    • UnnamedHarald profile imageAUTHOR

      David Hunt 

      8 years ago from Cedar Rapids, Iowa

      Giselle, I believe one of the backbones of Switzerland's neutrality has been based on compulsory military service and both men and women are eligible starting at age 18. I'm not sure whether all or a portion of those eligible and fit serve. That's a great question. Thanks for commenting.

    • profile image

      Giselle Maine 

      8 years ago

      Very interesting perspective - I admit up until now I hadn't really thought much about the role of Switzerland in World War II and I simply assumed that because of their neutrality that they were not in danger.

      Was the compulsory military service in Switzerland in response to the danger of WWII or was it a pre-existing tradition?

    • UnnamedHarald profile imageAUTHOR

      David Hunt 

      8 years ago from Cedar Rapids, Iowa

      Thanks for the awesome vote, Gypsy! I, too, didn't fully realize the depths the Swiss went to defending themselves-- or that the Germans almost invaded them, although I did know they had compulsory military service.

    • Gypsy Rose Lee profile image

      Gypsy Rose Lee 

      8 years ago from Daytona Beach, Florida

      Voted up and awesome. Lots of things I didn't know especially about Switzerland. I had always considered them as being a sort of hand off country and didn't think they'd be in any danger of invasion.Wish my parents had had some gold to leave in a Swiss bank before heading for the states. Thanks for sharing and passing this on.

    • UnnamedHarald profile imageAUTHOR

      David Hunt 

      8 years ago from Cedar Rapids, Iowa

      Thanks, Thomas-- I appreciate the comment.

    • Thomas Swan profile image

      Thomas Swan 

      8 years ago from New Zealand

      Fascinating article. Always good to learn something new.

    • UnnamedHarald profile imageAUTHOR

      David Hunt 

      8 years ago from Cedar Rapids, Iowa

      Thanks for commenting, wba108. The Swiss provided banking services for all belligerents, but, of course, regarding gold shipments, the Nazis were their best customer, as you say. There is a lot of controversy on this whole subject of Nazi/stolen gold, proving that people and companies of all stripes had their hand in the till. Oh, and thanks for the vote up.

    • wba108@yahoo.com profile image


      8 years ago from upstate, NY

      Voted up and awesome, I loved it! Sounds like a pretty accurate discription of the position of the Swiss in ww2. As you mentioned, the Swiss had to make some concessions to the Nazi's but make the invasion of Swiss territory seem a precarious venture at best. Perhaps the Germans were reluctant to invade another predominantly German nation for sentimental reasons and diplomatic reasons.

      Another good reason the Germans may have decided to leave Switzerland alone was that they needed a place to to hide all there stolen money in case they lost the war. Now there's something to think about!

    • UnnamedHarald profile imageAUTHOR

      David Hunt 

      8 years ago from Cedar Rapids, Iowa

      Pavlo, thanks for your great comment. You are absolutely correct-- the National Redoubt was a plan that utilized the impeneteratble Alps across Switzerland to defend against invasion. I will try to make that a little clearer. You are also right in thinking that not a lot of people are aware that Switzerland did nothing except declare their neutrality.

    • Pavlo Badovskyy profile image

      Pavlo Badovskyi 

      8 years ago from Kyiv, Ukraine

      Great hub! This article containes an information that not all people know. Just one thing which probably i did not understand well is that as far as i know National Redoubt was not a territory in mountains. It was a conception, a plan of national defence of country the basic idea of which was to go to mountaines, to move the line of defence to mountains too and as you noted "thereby making the invasion of Switzerland nearly pointless". Correct me please if my information is not correct.

    • UnnamedHarald profile imageAUTHOR

      David Hunt 

      8 years ago from Cedar Rapids, Iowa

      Hi, old albion. Thanks for reading and commenting!

    • UnnamedHarald profile imageAUTHOR

      David Hunt 

      8 years ago from Cedar Rapids, Iowa

      JKenny, funny you should mention Spain and Gibraltor. We can thank Admiral Canaris for contributing towards that lapse in judgment as well. He worked very hard dissuading the Nazis from invading Spain. As a military man he hated the Nazis and actively thwarted them wherever he could-- amazing given his high profile in the military and head of military intelligence. But you're right, I think. Despite any dissuasion from Canaris, I would have thought wrapping up the Mediterranean would have solved a lot of the Axis' problems! Thanks for the comment!

    • UnnamedHarald profile imageAUTHOR

      David Hunt 

      8 years ago from Cedar Rapids, Iowa

      Thanks for commenting, joanveronica. Yes, my understanding is that there were refugees turned away (especially Jews) but that refugees were also allowed in (including Jews) and a good many Jews smuggled in. It's very complicated.

    • old albion profile image

      Graham Lee 

      8 years ago from Lancashire. England.

      Hi UH. Written with your usual attention to detail. Excellent.


    • JKenny profile image

      James Kenny 

      8 years ago from Birmingham, England

      Excellent article- you very rarely find anything on Switzerland from the WW2. I really had no idea that about Operation Tannenbaum and the defensive preparations the Swiss made. I'm really surprised that Hitler didn't go through with the plan.

      In the same way, I'm surprised that neither Hitler or Franco at least tried to capture Gibraltar. If they'd have managed to get that, virtually the whole Mediterranean would have been theirs.

    • joanveronica profile image

      Joan Veronica Robertson 

      8 years ago from Concepcion, Chile

      Hi, just read your new article. Excellent as usual! I was under the impression that the refugees were accepted in Switzerland, although on the quiet. Neutrality is certainly difficult, and I know something about that, as there were some complicated situations in Chile over this issue, also Argentine and Brazil. Nobody could ignore the fact that there was a "world war" in progress. Voted up and interesting.


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