Travel: The secret heart of the Sahara

My driver didn't want to stop. Our guide had warned him about coupeurs de route - modern-day highwaymen - and he squinted with suspicion at the old man who ran towards us from a palm-frond hut, flapping his arms. Yet he looked harmless enough to me, and I asked the driver to stop. The old man told us that his baby grandson was very ill, and his daughter had set off with him by camel the previous night. But the nearest town was 100 miles away. If we met her en route, could we please give her a lift?

I had been driving for a week through an epic land of mountains, deserts and volcanic craters - with no roads. I kept thinking that in the United States all this would be a national park. In America, freeways slice through the wilderness, carrying you to the very edge of every natural wonder. But in the Chadian Sahara you're lucky to find a row of marker posts leading you through the sands, or around a minefield. Astonishing landscapes and rock paintings can be reached only by those with time, money, and one or preferably two Land Rovers.

And nothing puts off tourists like a war. Chad was in a state of war for nearly 30 years. In the Eighties it suffered famine, became known as the world's poorest country, and received a fleeting audience with Bob Geldof. Today Chad seems to be stable, but it urgently needs to develop its tiny economy. And it would love to see a few more tourists.

The capital, N'Djamena, has the colonnaded, sleepy air of a Mediterranean backwater. Its market sprawls around a large mosque, and there's a wealthier, tree-lined avenue with banks, a patisserie, and epiceries selling wine and tinned fois gras. If you want to hire a vehicle, you can - at a price. But I got lucky. I met Father Bessita, whose parish must be one of the world's remotest - the tiny Christian communities scattered among the Arab tribes of the Chadian desert. If I would pay for the diesel, he'd take me with him on one of his thrice-yearly jaunts.

We drove into the semi-arid Sahel, and then across savannah, where we saw - and, rather to my discomfort, hunted - gazelle. We crossed great tracts of desert, with dunes where the wind covered our traces within minutes of passing. We came upon a broken-down truck whose inhabitants rushed forward with empty water-bottles, and le pere took their grateful driver aboard. Then we ran out of water ourselves. We were crossing a plain where sheets of perilously soft sand alternated with tooth-loosening broken gravel. The heat was intense. I will never forget reaching the top of an escarpment and looking down on the desert town of Faya. Those thousands of tawny dots were trees, and trees meant water.

Faya has the makings of a popular tourist destination - a striking setting, some pleasant, rather Moorish buildings, a halo of palm fronds; it is close to desert, mountains and lakes. But there are artillery holes in its water-tower and there is no electricity. Chicken claws, goats' hooves and sardine cans litter the sand of the streets. You watch out for the scorpions, whose sting can kill a man. The only hotel offers, at pounds 18, dirty, airless rooms that would be over-priced at a fiver. But Faya is remote, so everything is overpriced there. Everything except the smuggled corn oil, tinned fish and petrol on sale at the Libyan Market.

Bessita is a big man, 6ft-something, fleshy and charismatic. On Sunday morning, he celebrated Mass in Faya's shady, shoebox-shaped church, his vast form in crisp white linen looming over the leaner congregation. Men played drums made from tinned shell casings, men and women swayed, girl- children danced, God became flesh and wine.

On Monday he headed out to his flocks in the eastern desert. And I went north west, towards Libya, having hired a battered pick-up Jeep and driver in Faya. My driver, Abdul, had never been this way before, and was nervous. I had good maps and a GPS (satellite position-finder), and was also nervous. By chance, we met a man who wanted to travel to the far side of the next stretch of desert, and he became our guide. We drove past orange dunes, and across white sand of utter flatness, driving under a full moon late into the night without any need for headlights.

It was mid-morning on our second day out of Faya when we met the old man who wasn't a highwayman, and noon when we found his daughter, sitting out the midday heat in a small grove of thorny desert trees. Her mother crouched beside her, and a boy tended the camel. The sick baby's eyes were acid yellow - presumably hepatitis. I put the women and baby into the cab, and climbed on to the back of the pick-up. Dark, sun-baked sandstone rose around us as the jeep climbed the barren foothills of the Tibesti Massif, the tallest mountains in the Sahara. It's a land of stark inhospitality, home to isolated and secretive tribespeople, mostly nomadic herders.

In late afternoon we saw before us a magnificent vision: a blood-red track through black rock leading down to the Zouar Valley, a broad sand plain locked in by rose-coloured sandstone cliffs 200ft high. At the checkpoint outside town, a soldier stared at me. I was quenching my thirst with a mango brought from Faya, and the soldier looked as though he wanted to hit me. "Don't eat that thing in front of me," he spat, in French. "I haven't seen a mango for four years. I haven't been south or seen my family for four years."

The fate of black African soldiers from the south posted to the north is unenviable. Much of Chad's civil strife has been along the ethnic-linguistic fault line between the black, usually Christian, south, and the Arab-Moslem north, a legacy of the French colonial carve-up. The genial and loose- limbed southerners are at a loss among the dour, self-sufficient Arabs. Mostly soldiers, they can spend many years posted in Tibesti, often unpaid for months on end. "What are we doing here?" I was asked by one desperate man who hadn't been relieved for 10 years. "Are we prisoners of war, or what?" Desertion is impossible; they'd soon die in the desert, and if they were caught they'd be shot. So they wait, smoking Libyan cigarettes and listening on short-wave radios to football results and reports of African wars.

I reached into the box and handed the soldier a mango. In delight, he almost danced back to his shack to eat it.

Zouar is a cluster of mud-block houses and palm-frond huts on a sand plain. Being responsible for a sick child brought home to me the statistics - that Chad has a severe shortage of doctors, and one of the world's highest infant mortality rates - 20 times Britain's. We found the doctor at his home in the military quarter. He examined the baby and diagnosed hepatitis and a severe lung infection. Would he live? I asked. "Oh yes," he said, "if we treat him. There's just one problem: medicines. I never have enough drugs. At the moment I haven't even a handful of paracetamol."

And so we spent hours visiting Zouar's unofficial pharmacies. People travel huge distances for medicines, clinging to the tops of trucks that smuggle goods down from the Libyan border. They face dehydration and attacks by bandits, and, understandably, they sell the drugs at exorbitant prices. We found most of what we needed, but one important drug was missing.

The next morning a guide took me through an uncleared Libyan minefield north, towards Bardai, deep in the Tibesti Massif. The roughly-hewn mountain pass scrapes the edge of a gigantic pink volcanic crater whose floor, far below, glistens white with salt. In this mountain desert there's a little moisture, and you see some wild flowers, and soaring black eagles. I explored for hours, amazed to be alone in a place of such extraordinary beauty.

That night we reached the palmy oasis of Bardai. I spent the night at the small French garrison, guest of six hospitable soldiers unused to welcoming European visitors. The captain was well versed in international politics, and it seemed reasonable to wonder what he and his men were doing in this remote spot. Was it their job, I asked, to monitor the Libyans, who are just a few miles north? In the late Eighties much of northern Chad was occupied by Libya, and General Gadafy's forces were thrown out only with French help. "No," he said stiffly, "Our sole task is to provide military assistance to the Chadian army." Tell it to the marines.

When I left Bardai the French adjutant, a Schwarzenegger-muscled Polynesian, presented me with a large box of drugs for the doctor at Zouar, including the very one needed by the baby boy. It was extraordinarily generous, and brought a lump to my throat. And so it was that my return journey to Zouar was a triumphant one. On the way I stopped to look at prehistoric cave paintings like those in The English Patient - cattle, elephants and giraffe daubed on the rock, recalling that 5,000 years ago these barren mountains were covered with lakes and trees. There are still subterranean aquifers, and one day the hills may be green again. One day, too, if Chad stays free of war, tourists will begin to discover this astonishing landscape. Until then, Tibesti will remain the barren and secret heart of the Sahara.

The Challenge of Chad

The Africa Travel Group (0171-387 1211) offers flights on Air France from various UK airports via Paris to the capital of Chad for pounds 910 including tax.

In N'Djamena you can hire reliable four-wheel drive vehicles, only with driver - check his mechanical expertise, and that enough spares are carried. Two-vehicle expeditions are safest.

There is no public transport, but you can rent a seat inside (or, for the suicidally hardy) on top of, a lorry or Toyota pick-up. Allow at least two months for the round trip. Trucks take up to 10 days to reach Faya, where you change vehicles for the journey to Zouar, and change again for Bardai. Take your own water and food; break-downs are frequent, and there is a recognised risk of armed hold-ups (much less if you travel in your own vehicle).