French emergency services are battling "zombie fires" that burn underground in the Fontainebleau forest and the Gironde department [1, 2].
These fires are dangerous because they remain invisible to the eye, hiding in root systems and soil layers for weeks before resurfacing in new locations [2]. This phenomenon forces authorities to maintain high alert even after surface flames appear extinguished.
The crisis intensified in mid-July 2026, with the initial fire starting on Sunday, July 12 [5]. In the forest of Fontainebleau, the blaze consumed about 2,000 hectares [4]. To combat the underground heat, crews are using soil-soaking techniques and tactical burns to deprive the fires of fuel [1, 2].
President Emmanuel Macron visited the site on Thursday to assess the response. The mobilization effort includes approximately 950 firefighters in Fontainebleau [3] and 120 military engineers deployed as reinforcements [2].
Reports on the status of the containment vary. Some officials said the fires were fixed but not fully extinguished [2], while others said the situation was controlled but not yet fixed [1]. Despite the uncertainty, the Prefect of Gironde said one day was "the first slightly optimistic day" [1].
In the Gironde region, the efforts have allowed 80,000 inhabitants across nine communes to return to their homes [1].
“These fires are dangerous because they remain invisible to the eye.”
The emergence of zombie fires in France highlights a growing challenge in wildfire management where traditional surface-level suppression is insufficient. By burning through organic matter in the soil, these fires create a persistent threat that can bypass containment lines, necessitating the use of specialized military engineering and soil-saturation tactics to ensure total extinction.
