Fort de Comboire, Military fortress in Claix, France

Fort de Comboire is an elongated Séré de Rivières fort of the second generation, built of cut limestone in the shape of a very stretched pentagon, at 515 m on the Comboire rocks above Claix. Behind the entrance gate and its ditch, a central courtyard is flanked by eleven bays of two-level troop rooms and two adjoining powder magazines. The two-storey barracks block carried the guns on its roof, and a dry ditch with caponiers surrounds the fronts.

Built from 1882 to 1884, the Fort de Comboire was the last of the seven forts forming Grenoble's fortified belt, erected after the 1870 defeat at Sedan to block an enemy advance on the city. It was designed by Colonel Cosseron de Villenoisy under the Séré de Rivières system, on a site 515 m up, and never saw combat. In 1887 it briefly bore the name Fort Monteynard.

The fort's name comes from the Comboire hill, from a term for a shallow depression and its edge. For a few months in 1887 it bore the name Fort Monteynard, after Louis François de Monteynard, first governor-general of Corsica and founder of the Saumur cavalry school. Since 2012 the association Les Amis du Fort de Comboire has maintained the site and organizes visits.

Access is by a single paved road starting at the hamlet of Les Garlettes, south of Seyssins, linked to the RD106d; the nearest bus stop is Seyssins, cimetière des Garlettes. The fort stands at about 515 m on the Comboire rocks and is almost invisible from the valley. Visits are organised by the association Les Amis du Fort de Comboire, which has maintained the site since 2012.

The fortress was originally designed to house around 358 soldiers and could accommodate about 20 artillery pieces. These numbers reveal the strategic importance this location held as a key defensive position for French border protection.