Fort de Dailly

Fort de Dailly
Part of Fortress Saint-Maurice
Western Switzerland
The Rhône valley with the Fort de Dailly on the heights to the right
Fort de Dailly
Coordinates	46°12′25″N 7°01′43″E / 46.20692°N 7.0287°E / 46.20692; 7.0287
Site information
Controlled by	Switzerland
Open to the public	From April 2014
Site history
Built	1892, expanded through the 1960s
In use	Not in use
Materials	Rock excavation
Garrison information
Occupants	Brigade de Forteresse 10

The Fort de Dailly is the largest component of Fortress Saint-Maurice, which is in turn one of the three principal fortified regions of the National Redoubt of Switzerland. Almost entirely subterranean, the Fort de Dailly was built in the Massif de Dailly to the east of Saint-Maurice beginning in 1892. With the Fort de Savatan, it comprises a fortress complex encased in rock high above the strategic Saint-Maurice valley, capable of commanding the valley from Chillon to Martigny. It is the central component of Fortress Saint-Maurice in terms of both its position and its military power. Construction began in 1892 and the fort became operational in 1894. The fort was nearly constantly upgraded with new artillery in increasingly secure positions. Following an incident in which three ammunition magazines exploded in close succession in 1946, the fort was repaired and upgraded with two fully automatic 150mm gun turrets with a range of 24 kilometres (15 mi). After reassessments by the Swiss Armed Forces of their requirements for fixed fortifications, Dailly was progressively closed down starting in 1995, with full closure at the end of 2003.

The Fort de Dailly is the largest part of a fortress complex extending the length of the Saint-Maurice valley, with coordinated fields of artillery fire and interlocking defenses. While most of these positions are detached from one another and are self-sufficient installations, Dailly and its neighbor Savatan are connected. The Fort de Savatan adjoins Dailly at a lower level, facing to the north,and is connected by an inclined funicular in the mountain. The forts at Dailly and Savatan were completed in 1894 and became the central elements of Fortress Saint-Maurice. They were progressively expanded and upgraded through the twentieth century. Over time, Dailly was equipped with an example of virtually every Swiss artillery piece and construction method, from rock-cut artillery galleries to revolving gun turrets.

The Fort de Dailly and surrounding installations were manned through their modern history by Fortress Brigade 10. Dailly and Savatan comprised Fortress Group 2, under Fortress Regiment 19 of Fortress Brigade 10.

Fort de Dailly is one of the largest and most heavily armed forts in Switzerland, and the central position in Fortress Saint-Maurice. The artillery fort is located on the end of the Dailly massif at a higher level than Savatan, with fields of fire to the north, west and south. The fort therefore is capable of firing on an enemy advancing southeast into the heart of the Alpine redoubt from the direction of Lac Léman, or northwest from the Great Saint Bernard or Simplon passes. Work began at Dailly in 1892. The entrance to the underground fort lies at an elevation of 1,400 metres (4,600 ft) at the end of 29 switchbacks. The fort initially was armed with six 120mm gun turrets with additional open artillery positions, including six additional 120mm guns on rail-mobile disappearing mounts. Two 75mm guns were mounted in casemates, while portable 53mm gun turrets occupied prepared surface positions. Dailly was upgraded with 105mm artillery during the 1940s, with as many as ten 105mm guns in casemate positions. Flanking coverage from across the valley was provided by the Fort du Scex.