The wildfires triggered the detonation of deadly Second World War weaponry that had lain hidden beneath the ground for decades. Mega wildfires in southern France detonate more than 400 unexploded shells left behind from the Second World War. The intense heat generated by the fires acted as a catalyst, triggering explosive charges dating back to the Second World War and exposing firefighters and emergency personnel to a significant risk from flying debris and unexploded ordnance. This extreme combustion event caused the fire to spread beneath the surface, where it came into contact with unexploded munitions from the Second World War that had remained buried beneath layers of forest humus. This transfer of heat by conduction raised the temperature of Second World War metal casings beyond the point at which they remained chemically stable.