Earliest records show that the position of the village of Tournoux was a strategically important one, with the tiny plateau offering food and watering facilities to armies crossing the Col de Larche from modern day Italy and the Col de Vars.

At the time, the use of cannons was relatively limited and such fighting as there was would have been hand-to-hand or musket-fire only, with the presence of the soldiers being the major deterrent to invasion over the cols.

The lowest level is the barracks (Caserne Pellegrin) at 1300 m next to the main road from the Cols (Larche and Vars) to the village of la Condamine and the towns of Jausiers and Barcelonnette.

There is a covered roadway that links the Fort Moyen with the village of Tournoux, providing another means of entry and exit – this way is very heavily protected with loopholes and gun emplacements.

The Fort Supérieur and the Batterie du Clos des Caurres are protected by a scarp/counterscarp wall system and by sliding drawbridges, which withdraw into the guardhouse on rollers when closed to traffic.

[2] A project to locate three 145 mm guns in a casemate in Fort Grouchy firing towards the Col de Larche was proposed in 1929, but not pursued.

[2] The Batterie du Clos des Caurres 44°28′14.51″N 06°44′55.51″E / 44.4706972°N 6.7487528°E / 44.4706972; 6.7487528 is even higher than Fort Supérieur, at 1,780 metres (5,840 ft) and contains the main armament of the complex.

Prior to World War I, efforts were made to provide concrete cover over critical areas, which were not completed in 1914.

Armament consisted of four 95 mm guns[4] The Batterie du Vallon Claus 44°30′43″N 06°43′43.32″E / 44.51194°N 6.7287000°E / 44.51194; 6.7287000 is located 5.2 kilometres (3.2 mi) to the north of the main complex.

[2] The garrison comprised 75 men, housed in a barracks nearby, connected to the main fort via a subterranean ammunition magazine.

The local economy also benefited from the presence of the forts and the army, both during construction and afterwards, the villages of la Condamine and Gleizolles in particular.

Above the entrance roadway and the soldiers’ barrack block are arched structures (looking a bit like tall, thin bridges) attached to the rock face.

Later in the war, in October 1944 the fort was occupied by the German army as Free French forces approached up the Ubaye valley from their invasion in southern France.

As the French got closer, the Germans destroyed the water and electricity supplies and looted much of the fittings of the fort for firewood etc.

The French Army spent the very cold winter of 1944–45 in the Fort de Tournoux, before finally attacking the Germans and extracting them from the Maginot ouvrages in April 1945.

From 1947 until 1991, Domaine Militaire signs were left to scare away potential explorers, while the Fort Supérieur was well protected by its walls and barbed wire.

The forts remained in a fairly good state of repair (although open to the elements) until it was purchased by the local government from the military.

The Batterie des Caurres now has an up-to-date use as a relay for TV and mobile phone signals to the local area.