The concept of "réduit" is a recurring theme in Swiss defense theory. Having avoided fighting during World War II, Switzerland retained the concept for its plans of resistance against a putative Soviet invasion during the Cold War, thus shaping a part of the national folklore, and a strong influence in the Swiss concept of neutrality.
Fortification of the Swiss alpine region began in the 1880s, shortly after the opening of the Gotthard railway. Forts similar to those of Belgian military engineer Henri Alexis Brialmont were built at Airolo, the Oberalp Pass, Furka Pass, and Grimsel Pass, all in the central Alps. Additional positions were constructed in the area of Saint-Maurice, using mining and tunneling techniques in the steep mountainsides of the glacial valley.
Following World War I, there was little Swiss interest in further fortifications. However, during the 1930s as France built the Maginot Line from the Swiss border to Belgium, and Czechoslovakia built the Czechoslovak border fortifications: Switzerland re-examined its need for fixed defenses. At the same time, job creation programs became desirable as a result of the worldwide Great Depression. By 1935 design work began, and in 1937 construction began on the expanded Alpine fortifications, the Border Line, and the Army line fortifications.
General Henri Guisan developed a strategy for the defense of Switzerland that recognized Switzerland's limited resources in equipment and manpower compared to its potential adversaries. Guisan proposed a delaying strategy in the broken terrain of the borders to keep an invading force out of the open country in the central plateau for as long as possible, allowing an orderly retreat to the secured Alpine perimeter. Once the retreat to the Alps was complete, the Swiss government could remain in hiding for an extended time. Accordingly, the border fortifications were improved with major programs along the Rhine and at Vallorbe in the Jura. The strategic Alpine nodes of Saint-Maurice, Saint Gotthard, and Sargans were identified as the primary points of access to the Alpine redoubt for a potential aggressor. While Saint Gotthard and Saint-Maurice had been previously fortified, the area of Sargans was newly vulnerable, owing to a drainage program of former wetlands along the Rhine that would now provide easy access to the eastern Alpine gateway at Sargans.
Debate continued over the extent of the Redoubt under the Guisan plan. A proposal was developed by officers from German-speaking cantons, advocating a more compact redoubt. This was overcome by a proposal, authored by Guisan's chief of staff, Colonel Samuel Gonard, whose plan ratified the Saint-Maurice - Saint Gotthard - Sargans strategy, prefaced by a defense in depth. Additional impetus was provided by the fall of France in June 1940. Two days after the French surrender, on 23 June, the border zones were reduced in priority in favor of the "advanced position" or Army Line. The army was shifted to the center of the country, leaving industries and population centers relatively unprotected. The final Guisan plan, adopted on 12 July 1940, defined an organized retreat to the Alps, where supplies would be stocked for an indefinite resistance with no thought of further retreat. On 25 July 1940, the Swiss defensive plan was disseminated, dictating a fallback to the Alps in the event of an Axis attack, focusing in particular on the Gotthard massif and destroying all access points as necessary once inside.
The National Redoubt strategy was emphasized on 24 May 1941. Until this time only about two thirds of the Swiss Army had been mobilized. Following the swift overrunning of the Balkan countries by German forces in April 1941, in which relatively low mountains had proven to be little barrier to the aggressive German forces, the entire Swiss army was mobilized. The Swiss, lacking a significant armored force, drew the conclusion that withdrawal to the Redoubt was the only sound course. Any actions in the Central Plateau would be delaying actions only. This was publicly reported after Switzerland was surrounded by German and Italian forces, Guisan revealed on 25 July 1940 at the so-called Rütlirapport, a historic and highly-symbolic meeting of the Swiss army staff and the entire officer corps at the founding site of the Swiss confederation, that in case of attack the Swiss would only defend the high Alps including the important transalpine roads and rail links. As a last resort, the army would make these routes useless to the Axis by destroying key bridges and tunnels. This plan meant that the populated lowlands - including the economic centres of the country - would be effectively ceded to the Germans. The gold reserves of the Swiss National Bank in Zürich were moved farther away from the German border, to the Gotthard Pass and Berne.
World War II
Camouflaged infantry fortification in Sufers (machine gun bastion left, antitank gun right, housing, and connecting tunnel underground)
The National Redoubt assumed great importance to the Swiss in 1940, when they were entirely surrounded by Axis powers, and hence effectively at the mercy of Hitler and Mussolini. The National Redoubt was a way to preserve at least part of Swiss territory in the event of an invasion. The Redoubt was to be manned by eight infantry divisions and three mountain brigades; the Swiss practiced for war by imitating the battles occurring around them.Switzerland's Réduit strategy during World War II was essentially one of deterrence. The idea was to make clear to the Third Reich that an invasion would have a high cost. Simultaneously, economic concessions were made to Germany in the hope that the overall cost of a German invasion would be perceived as higher than the potential benefits. Despite this, it is clear that Hitler intended to invade eventually and that the Allied landing at Normandy as well as the difficulties faced in invading Russia were pivotal in merely delaying an invasion. Concessions included a national blackout, and the destruction of a secret German radar system that had accidentally landed in Switzerland in exchange for a dozen aircraft. In their invasion plan, Operation Tannenbaum, Germany planned to capture Geneva and Lucerne while Italy would capture the Alps; the two countries would divide Switzerland.
Swiss policy during the Cold War adopted a more aggressive defense of the borders, relying less on a retreat to the mountains. While Switzerland was again surrounded by an alliance, NATO was not considered a threat to Swiss national existence; however Warsaw Pact nations were considered threats. The Swiss strategy sought to exact a high price from any direct ground attack on Swiss territory. Control of the Alpine crossings remained a cornerstone of the Swiss strategy of neutrality. The dense network of passive and active barriers and large and small fortifications allowed considerable flexibility in the disposition of Swiss forces, and represented an almost optimal scenario of defense in depth.
The strategic importance of the Alpine crossings had only increased since the Second World War, and any incursion by Warsaw Pact forces would require that they either be taken, or that terms for their use would need to be agreed upon to the satisfaction of Switzerland.
In 1953, Swiss policy was formalized to place greater emphasis on the defense of the borders and population centers, and to extend the concept of defense in depth, pioneered in the Redoubt, to the entire Swiss territory. This corresponded to an unspoken reliance on cooperation with NATO to secure the flanks of Swiss territory and to resupply Swiss forces, which already purchased equipment from members of NATO. The Redoubt, with its determinedly neutralist connotations, lost priority.
Many billions of francs have been invested in building the fortifications in the mountains, which are partly still used by the army. The most important buildings of the Réduit were the fortifications of Sargans, St. Maurice, and the Gotthard region. The caverns of those time were equipped with the needed infrastructure, beside cannons and howitzers they consisted of dormitories, kitchens, field hospitals, rooms for the sick and bakeries; as well as providing enough space to accommodate 100 to 600 soldiers for up to several months. Because tensions between the western countries and the USSR cooled down and bunkers became increasingly obsolete because of newer weapon systems, a great number of the Réduit buildings were closed in the aftermath of the Cold War in the mid-to-late 1990s and early 2000s. Some of them have been reopened as museums and can be visited.
Comparison with contemporary projects
The National Redoubt fortifications, when compared to contemporary French, Belgian, German, or Czech fortifications, were much more extensive and heavily armed than the Maginot Line, the Belgian border fortifications, the Siegfried Line, or the Czechoslovak border fortifications. While the Maginot fortifications were typically armed with short-barreled 75mm fortress howitzers or 120mm mortar/howitzers, the Swiss fortifications were armed with 75mm and 120mm guns, upgraded in the 1950s to 105mm and 150mm guns. The Swiss guns were typically casemate-mounted or turret-mounted long guns, not howitzers, and were more akin to naval guns than fortress guns. Because they were typically mounted on inaccessible cliffs or plateaus with an advantage of enfilade over any possible opposing force, they were not exposed to infantry attack or direct artillery fire and could afford to have exposed gun barrels. The French positions, which could be targeted by anti-tank weapons or infantry, avoided any exposed gun tubes.