Prosper Demontzey, “Hercules” by Cauterets

In every village, in every region, there are people who leave their mark on history.

Prosper Demontzey, undeniably, is of this caliber. By directing  the gigantic consolidation works of the mountain which threatened to collapse onto the Cauterets thermal baths at the end of the 19th century, Demontzey saved the economic future of the village.

Through this brilliant feat and other projects of the same type, this ingenious engineer was the precursor of Mountain Terrain Restoration techniques.

1884, the future of the spa town in peril

From the 1820s onwards, thermalism flourished in the Pyrenees . Cauterets opened its first modern thermal baths at La Raillère in 1828. These were followed by the Thermes de César (1844), the Thermes de Pauze-Vieux (1853), and the Néo-Thermes (1879). The spa towns became holiday destinations for high society , and spa-goers filled the grand hotels.

But in the spring of 1884, the future of the Raillère thermal baths suddenly darkened. For several days, large granite blocks broke away from Mont Péguère and pierced the roofs of the establishments like cannonballs. Naturally, the spa-goers fled…

The steep slopes overlooking the Raillère thermal baths, made of limestone and granite, are indeed prone to frequent rockfalls and avalanches .  This natural instability is exacerbated by deforestation (for firewood) and the regular harvesting of ice in this area near the village.

Engineer Demontzey called to the mountain's bedside

Engineer Prosper Demontzey , head of the General Inspectorate for the Restoration of Mountain Lands (RTM), was urgently dispatched to examine the situation.

He advocates a simple, albeit ambitious, remedy: stabilizing the land by combining reforestation with the creation of tiered grassy lawns on terraces supported by massive stone walls. For reforestation, he recommends planting larches, a non-native but very hardy conifer.

Fortunately for Cauterets, since the laws of Napoleon III of July 1860 on reforestation in the mountains, and thanks to the emperor's taste for the Pyrenees, Demontzey has all the authority and the necessary funds to carry out his work.

He even exhibited a model of it at the Universal Exhibition in Paris in 1889. His project made a strong impression, subsequently earning him visits from many celebrities to the construction site.

A Herculean undertaking

Like other great Pyrenean works at the end of the 19th century, such as the Pont Napoléon in Luz or the Pic du Midi de Bigorre , the consolidation of Mont Péguère is worthy of the labors of Hercules!

Work began in 1885. First, an access road was built: no fewer than 78 switchbacks (still numbered!) wound their way up the south-east side of Mont Péguère, complemented by a stone shelter for the workers.

The work to reinforce the valley with stones began in 1886. Local rock was used, quarried on site and transported by hand or via a small cable car installed by the RTM (Mountain Transport Network). Dry stone retaining walls were built, and nursery strips were prepared for reforestation and grassing.

The grass cover is taken from the Cambasque slope : squares of grass are thus cut out and replanted in the Northeast valley. The beginnings of the lawn transplant!

This arduous and slow work motivated the installation of a mini railway This railway, brought in pieces and assembled on site, allowed the movement between the two slopes of wagons transporting slabs of grass and blocks of stone.

This titanic construction project lasted more than 10 years, until 1892, creating colossal walls, supported by 7 km of mule track and 14 km of forest trails.

The Cauteretsian scholar Alphonse Meillon would write about Prosper Demontzey:

"He healed the mountain's wound. There, he made the blocks that desperately wanted to leave move; here, he 'under-walled' those that still held on; further on, he planted grass on the sandy surfaces; elsewhere, he built stone facings.".

A pioneer of modern reforestation techniques, author of several treatises on the subject, and renowned far beyond our borders, Demontzey was truly a benefactor to the spa town of Cauterets. The hiking trail at the foot of Mont Péguère, and a stone at the edge of the forest near the Ceriset waterfall, now honor his memory.

Mont Péguère and La Raillère today

The structures designed by Demontzey are still standing and holding up , even though over the next 130 years they required reinforcement: initially with concrete formwork, later with pressure-injected concrete, and steel netting stretched across the cliff face upstream from the shops at La Raillère. Even today, the authorities still keep a close eye on this mountain!

the Raillère thermal baths
had to be The 3,200 m² building was preserved, however, as a testament to Cauterets' thermal history and Art Nouveau architecture. Raillère also retains its small train station, a remnant of the former tram line.

In 2019, the Saint-Savin trade union commission sold the La Raillère thermal baths to the Russian artist Andrei Molodkin, who had already been living in the Hautes-Pyrénées since 2014, in the former Maubourguet foundry, which had become the experimental art venue "The Foundry".

For the same safety reasons, a municipal decree has prohibited hikers from accessing the Pic de Péguère since 2008. This decree is still in effect today. It's a shame because the 360° view from up there is absolutely incredible! See the photos, taken before the ban by hikers Jean-Paul and Mariano : from the summit of the Pic, you can admire the entire valley from Lac de Gaube to the north face of Vignemale!

Let's hope that one day the Demontzey switchbacks can be climbed again, to the great joy of hikers!