The desperate search for Congo's hidden victims

Outside the headquarters of Virunga Park, three men with determined expressions are loading camping equipment into two pick-up trucks. Watching from the steps of the station are two park rangers carrying assault rifles. Rolled-up mattresses are tied down, jerry cans of fuel and kit bags are stowed. No one is chatting and everything is done quickly. Everyone has the same sense of urgency.

These men are the last line of protection for the most important population of mountain gorillas in the world. They have just got the order for which they have been waiting for nearly 15 months.

In the midst of the war in eastern Congo a deal has been brokered to allow the park rangers back into the mountain range where they have been prevented from going since September of last year when it was overrun by the rebel CNDP army of Tutsi general Laurent Nkunda. Since then, there has been only one recorded sighting of a silverback – an adult male – by the staff whose main purpose is to protect one-third of the world's remaining mountain gorillas.

Africa's oldest park, and arguably the most important nature reserve in the world, is home to spectacular mountains, volcanoes and ancient forest, but it has also become a war zone. The nearly constant series of conflicts that spilled across the border from Rwanda after the genocide in 1994, have worsened dramatically in the past year and a half, driving Virunga's rangers out of one station after another until finally overrunning the park headquartersat Rumangabo.

One month ago, the station came under attack during a pitched battle between government forces and General Nkunda's forces. There are still spent shell cases in the grounds of Rumangabo from the fighting which scattered the rangers and their families. One young girl was hit in the chest by a stray bullet.

The wardens, like so many others in eastern Democratic Republic of Congo (DRC), were forced into the cholera-filled refugee camps that sprung up around the city of Goma. Only now have they been able to return. Diddy Mwanake was one of the first to come back and is impatient. The 46-year-old knows more about Virunga's great apes than almost anyone alive but he has been cut off for too long from the creatures he has been observing, cataloguing and fighting for since joining the service 17 years ago. His mind is alive with imagined horrors. "Of course we're afraid of what we're going to find, it's now been more than year where we can't take care of them."

He reels off a list of infectious diseases and hunters' snares that might have befallen the apes. Then his thoughts turn to the war. "With artillery shells and high-powered weapons I have to wonder if they have been hit? They could be out there wounded."

Rumangabo sits on a promontory commanding impressive views – volcanoes rise out of dense forests to touch the clouds. On the one side, Nyirangongo, which erupted four years ago to send lava flows into Goma dominates the landscape, while on the other rises the 13,000ft (4,500m) tall Mikeno, where the gorillas live.

Diddy hasn't yet said a word about the dangers that the rangers and their families have faced in a war that came to their doorstep. He and the other rangers only got back to the station last Friday.

"I was here when the fighting reached the gate," he says. In the ensuing chaos everyone became a target. "They (CNDP) came from everywhere. When there is shooting bullets don't distinguish between people." He says they spotted an opening and fled. For many of the rangers, it was the beginning of a 25-mile trek to safety through the bush.

"The rangers were the first victims of this war," says Emmanuel de Merode, a conservationist who was recently made chief warden at Virunga. Sitting in his empty office in the ransacked headquarters, the 38-year-old Belgian says the fighting and the abandonment of the park's headquarters has marked the lowest point in its history, capping a traumatic period which began with the murders of seven gorillas in June and July of last year. The shocking pictures of a murdered 500-pound silverback, named Senkwekwe, being carried on wooden poles by grieving villagers sparked a global outcry. They also revealed the vicious and lucrative charcoal trade that Mr de Merode describes as the "greatest threat to the park".

There are an estimated 720 mountain gorillas left in the wild. More than half of these are in the Virunga volcanoes bordering DRC, Rwanda and Uganda – with the remainder 15 miles north in Uganda's Bwindi impenetrable forest. The 2,000 acres (800,000 hectares) of Virunga form a corridor stretching 155 miles between north and south Kivu lakes. Some one million people displaced by a decade of war live in nightmarish camps on the fringe of the park. They are completely reliant on charcoal for their cooking and heating, creating a trafficking industry thought to be worth £20m per year. That money is enough, along with illegal mining operations to sustain the two main rebel armies: General Nkunda's CNDP and their sworn enemies, the FDLR, made up of Hutu guerrillas, active in the 1994 genocide, who fled Rwanda to regroup. Added to the mix is the corrupt and chaotic Congolese army who have used military trucks to transport charcoal.

For once, it was not poachers who were to blame for the gorilla murders – Senkwekwe's hands and feet had not been lopped off for trophies. The darker truth was that the gorilla families had been murdered as a warning to one brave faction of rangers still doing their job by a rival faction who had sold out to the charcoal dealers.

More than 100 rangers have been killed in the line of duty in the past 10 years, some arrested and tortured to death by militiamen. Those that wanted to protect the gorillas knew they had to preserve the forest. Attempts to salvage the situation while meeting the needs of the densely populated area have included planting sustainable eucalyptus trees and importing butane gas but all have foundered on the incessant war.

"No forest means no gorillas," says Mr de Merode. Already a huge section of Virunga's hardwoods have been eaten by this voracious industry. The rot went right to the heart of the park service itself and former chief warden Honore Masharigo is now in jail awaiting trial on charges of charcoal trafficking and killing gorillas. Although he won't say as much, that is why an outsider like Mr de Merode – who worked for the WildlifeDirect NGO – has been made chief warden by the Congolese Institute for the Conservation of Nature.

Since taking over, he got permission from the government in Kinshasa to stage private talks with Nkunda to regain access to the vital Mikeno section of the park. The renegade general is acutely aware of his international image and his own soldiers face a death sentence for injuring the prized apes. After talks with the new warden the unpredictable soldier-politician finally relented. So far, Mr de Merode and the 650 Virunga rangers have been forced to rely on second-hand reports from amateurs who paid their way into Mikeno where General Nkunda has been using some former rangers who defected to the CNDP.

Spirits are now high at Rumangabo. Within the last few days the Belgian conservationist led a posse of rangers back to their former patrol post at Bukima, inside the Mikeno sector of the park. Outside, Mr Mwanake is talking to Innocent Nburanumwe, another veteran ranger. They remain fretful over the situation and aware that the crisis could take another turn for the worst. "When there is a war there is no certainty, no security. We are not sure when we go to sleep if we will wake up in the morning."

Another nagging worry remains: the gorillas simply won't be there any more. Mr De Merode is refusing to think that way. Over the next month he and his staff will conduct a census of the mountain gorillas, hoping to find the population of roughly 200 unaffected by the tempest that has raged around them in the past 18 months. He says: "We've not had reports of any gorilla killings. It's incredibly exciting and any day now we're expecting good news."