The Promenthouse line, famous today by its situation next to the Toblerones Trail, is also part of the frontier fortifications. It is the most westerly of lines running in an arc from Sargans along the Limmat, the Rhine and the Jura chain to Versoix.
After having studied the territory in 1936, it was as of 1937 that the first reinforcements of the terrain were established. Rail sections were driven into the sides of the river by engineer troops that provided a form of resistance to the armed forces.
In October 1939, the first contracts for the building of these bunkers were signed with civil engineers. During the periods of the mobilisation, the line was constantly reinforced and improved by soldiers of the frontier Brigade 1 and two battalions of sappers who were called in as reinforcements.
As of 1941, the rails were replaced by the toblerones and the mines were placed on bridges. Today, a dozen of these bunkers and about twenty barricades and antitank obstacles are still in possession of the Confederation. Amongst the most remarkable elements are the camouflaged houses called the Villa Rose and the Villa Verte, as well as the numerous firing positions that were built along the line of the anti-tank obstacles.
Construction of the line
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1937
Railway lines start to be driven into ground as anti-tank obstacles.
(5464 pieces in all over 18 km) -
1938
Construction of anti-tank walls the length of the river Serine at Vich and at Pont Farbel. -
1940
Cavities for irons rails are cast within the concrete slabs as anti-tank barricades on certain paths, roads and bridges. -
1940-41
Construction of the bunkers ("Villa Rose" handed to the troop on 14.10.1942). -
1940-42
Construction of the tetrahedrons, known as "Toblerones", (2700 units covering 8km) that replaced the rails.
Anti-tank wall along the route from Bassins to Arzier.
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1943
Construction of Infantry works north of Bassins. -
1944
Construction of the line of Defence of La Dullive.