Fort du Larmont Inférieure, Fort Mahler – La-Cluse-et-Mijoux, France


Following the N57 from Besançon (France) to La-Cluse-et-Mijoux (France) en route to Switzerland, the road cuts through the Larmont, a stretched out mountain peak of the Jura in the beautiful area of the Haute Doubs. The road passage is guarded by two forts situated on both sides of the mountain ridge above.
On the South-Western side lies the impressive Château de Joux, the oldest and largest of them both, clearly visible and overlooking the surrounding area. On the North-Eastern side, at an altitude of 1032 meters, lies Fort Mahler a.k.a. Fort du Larmont Inférieure.

Construction of Fort Mahler

Fort Mahler at la-Cluse-te-Mijoux, France
Fort Mahler at la-Cluse-et-Mijoux, France

“Fort Mahler” or as it was originally called “Fort du Larmont Inférieure” was built between 1843 and 1851 to cover the flank of “Château de Joux” or “Fort de Joux” in case of an attack. In the years before, Fort de Joux had already fallen twice (to the Austrians and the Swiss) whom both successfully attacked it from this North-Eastern ridge and plundered the fortress. Fort Mahler had to prevent a third attack with the same strategy. For this reason, Fort Mahler lies far more secluded from view and is harder to reach than her older and larger sister.

View from Fort Mahler France
View from Fort Mahler looking out towards Chateau de Joux

Starting from 1852, Fort Mahler was manned by 60 to 90 soldiers, a rather small number compared to the 400 to 700 men that were garrisoned at Fort de Joux. Originally the fortress consisted of multiple buildings, which also included a large 4 story barrack building to house the garrison. Food was provided by the local towns. Water was supplied by storing rainwater in an underground water tank.
It’s armament consisted of some heavy guns to support Fort de Joux and infantry weapons for close defense.

Living conditions on the mountain were tough, especially during the winter season. Thanks to the harsh climate, the fort had a very high humidity percentage, which resulted in many of the occupants suffering from pneumonia, with a far above average fatal toll. A lot of effort was done to improve the ventilation system of the fort to prevent this.

In 1871, Fort Mahler proved it’s use when both forts successfully withstood an attack of the Prussian army, resulting in 1200 mostly Prussian victims. A memorial of this event can be found at the end of the passage in La-Cluse-et-Mijoux.

Renovation in the 19th Century

At the end of the 19th century the fort was completely renovated conform modern standards. To better protect it against artillery fire, a large part of the Fortress was earthed and some parts reinforced with concrete. Also the entrance was moved to the back.

Fall Rot: the German invasion of France

Although it was modernized in the century before, the adaptations still proved useful when the Germans invaded France. On June 1940 a column of the Wehrmacht came down the road from Besançon, spearheaded by a tank and a side-car motorcycle. When the vehicles moved down the passage towards La-Cluse-et-Mijoux a shell fired from Fort de Joux took out both. This started off a fierce fight between the Germans and both Fortresses, which lasted until the Armistice was signed and the fortress commanders finally had to surrender.
It is notable that their resistance allowed many French to escape to the ‘free’ French zone using the corridor between the Fortresses and the border of Switzerland.

Fort Mahler today

After the Second World War Fort Mahler was abandoned by the French Army in 1947. In 1958, Fort Mahler and Fort de Joux were both sold in a package deal to the Community of La-Cluse-et-Mijoux for tourism purposes. Unfortunately, only Fort de Joux has been exploited so far and received some restoration work, which was going on during our visit.
Although Fort Mahler also has had some minor work done to prevent it from total collapse in 2010, we couldn’t find any sign of further restoration.
The fort is clearly in a state of decay.

Entrance of Fort Mahler la-Cluse-te-Mijoux, France
Entrance of Fort Mahler la-Cluse-et-Mijoux, France
Entrance of Fort Mahler
Detail of the main entrance of Fort Mahler.
Fort Mahler wall detail
Fort Mahler wall detail left of entrance. The top is heavily deteriorated.
Fort Mahler Trench
View from the bridge into the trench. In the far corner gun openings are visible for it’s defense.
Bridge to entrance of Fort Mahler
Bridge to entrance of Fort Mahler.
Main hallway Fort Mahler
A peek inside the main hallway of Fort Mahler.
A wall in decay at Fort Mahler in la-Cluse-te-Mijoux, France
A collapsed wall at Fort Mahler in la-Cluse-et-Mijoux, France
Fort Mahler detail of a small observation tower
Fort Mahler detail of a small observation tower.
Looking out over the trench around Fort Mahler
Looking out over the trench around Fort Mahler
Bridge collapsed of former entrance of Fort Mahler
The bridge towards the former entrance on the West side of Fort Mahler has collapsed. We could view the wooden structure lying further down on the steep mountainside.

Visit Fort Mahler

As the pictures clearly testify, the fortress is in decay and left to it’s destiny. There are some information sources who state that there are plans to renovate the site in the future, but it is unclear when. In the meantime, be very careful when entering the fort itself, because some parts of the building are on the verge of collapsing.

The Walking Trail

A footpath leads up to Fort Mahler from the N57. It starts at the small bunker building at the foot of the steep slope in the center of the passage. You can park your car at the side of the road and start the climb, but be warned; it is a rather steep climb of about a 150 meters with 230 steps (according to the sign on top). Just follow the steps left of the anti-tank wall leading up the mountain side and you can’t go wrong. Wear sturdy footwear.

Small bunker in the passage below Fort Mahler, France
Small bunker in the passage below Fort Mahler, France. Notice the adapted gun embrasures on the right corner.
MG stand Fort Mahler-France
Close up of adapted MG stand – Fort Mahler-France
Steps to Fort Mahler
Steps leading up to Fort Mahler
Remains of another construction
Remains of another building at the top of the stairs
View down the stairs
View down the stairs
Walking trail up to Fort Mahler
Walking trail up to Fort Mahler. Now it really begins..
Here and there the railing has been swept away by falling rocks
Here and there the railing has been swept away by falling rocks. Stay right.
End of the walking trail to Fort Mahler France
Reaching Fort Mahler at the end of the walking trail. The sign indicates the 1032 m altitude and 230 steps of the path down.

Unless you are an experienced hiker, you will want to take a break for a minute to catch your breath once you are on top. The view from up here feels very rewarding though and you’ll be more than happy to rest and enjoy it for a while. The view towards Fort de Joux is spectacular.

Dirt Road

Studying the map more closely, I also found a dirt road leading up to the fortress, although I cannot confirm if it is publicly accessible or that it is allowed to drive with a car. It starts from the parking lot of the Post Office (La Poste) at La-Cluse-et-Mijoux on the left of the building.



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2 thoughts on “Fort du Larmont Inférieure, Fort Mahler – La-Cluse-et-Mijoux, France

James Williams on

Very useful. I have driven past this château for years and always wanted to see inside. Thanks… Also very interesting.

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