The rains start in October in Katanga province, with huge drops that fall as they do only in the tropics, straight and hard, like a hail of ball bearings.

Water pools. And then, restlessly, the runoff begins to move. It slides northward across an immense red savanna, once home to an African king who played two colonial powers off against each other, only to be shot for his cleverness. The water creases into rivulets, which soon merge into small, sluggish creeks. One of these creeks flows past a mine that once supplied the uranium for America's first atom bomb. Another, snaking miles away on a plain of strange, bone-white mud, sluices between the bare, spindly legs of Paul Katoji."Gold," whispers Katoji, holding up a grain of shiny metal on the tip of his thumb.

The skinny prospector stares hungrily at the glinting crumb. He is poor and has a wife and four small children to feed. Like scores of other men, he scratches in the stream for gold, surviving on the mercy of the tributary. The stream, fed now by hungry men's sweat, drains the tailings of an enormous mine closed by war. These dregs hold untold tons of gold along with an estimated 180,000 tons of the strategic metal cobalt. Every day Katoji, clad in patched shorts, sifts his water-wrinkled fingers through a discarded treasure worth more than a billion dollars.

In this way, from this wretched paradox, the Congo River is born.

If rivers can be the biographers of a landscape, gathering not just the silt but the stories of the nations they traverse, then the tale of the Congo River today is one of epic, almost hallucinatory tragedy: For more than two years now, one of the world's mightiest waterways has gushed through the heart of Africa's most dangerous and debilitating war.

Rising from Congo's rich mineral fields, the Congo River curves north into a primordial jungle that now absorbs the racketing gunfire of at least a half-dozen dueling armies. The river's currents, so massive they bulge 5 feet with the tug of a full moon, glide past ruined cities and abandoned villages. Nearly 3,000 miles later, swollen now by some 7,000 miles of tributaries, they reflect the skyscrapers of Kinshasa, a capital city where idled barges crammed with refugees provide a backdrop for water-skiing diplomats and relief workers.

Dip a finger into the river's burbling headwaters; it isn't the distant pounding of the Atlantic surf you feel, but the faint vibrations of war.

Little seen by outsiders, this clash over Africa's vast center has been muffled by the remoteness of the battlefield--a trackless forest bigger than Western Europe. Yet as faraway as it may seem, the war is perhaps the defining conflict in modern Africa, a struggle over power and wealth that heralds a depressing new era of instability for the world's poorest continent.

Diplomats call it "Africa's First World War" because the armies of seven nations, three squabbling rebel groups and a rabble of militias are ensnared in fighting that has caused hundreds of thousands of deaths.

The rebels, mostly boys in gum boots, have occupied the eastern half of the Democratic Republic of Congo, Africa's third-largest nation, with the help of troops from Rwanda, Uganda and Burundi, who claim to be protecting their flanks from marauding guerrillas. The western and southern half of the million-square-mile country remains in government hands, but only with military support of allies Angola, Zimbabwe and Namibia.

It is a war of rusty barges tricked out with artillery that sink in river skirmishes ignored by the world; the warm currents, watched over by squalling gray parrots or shrieking monkeys, carry away the dead.

It is war where jets scratch the equatorial skies, dropping a lone bomb, like an egg, into a rainforest second in size only to the Amazon. A war where thatched villages and tin-roofed towns fall and are retaken in a scramble for gold, diamonds and timber as much as for political power.

In this festering tropical garden, millions of Congolese hunker in the shadows by armed strangers who come from far-off lands. In Katanga's provincial capital of Lubumbashi, located 150 miles from the Congo River's source, Zimbabwean soldiers relax from lonely guard duty at remote diamond mines. Crew-cut Asian men in cheap shoes hurry past on dirt sidewalks--North Korean military trainers who drill the troops of Congolese President Laurent Kabila in exchange for diamonds or, according to some, uranium.

Far from the towns, out in the immense jungles, ghastly rumors drift through the forest like foul swamp gas--tales of atrocities committed against civilians trapped in the chaos.

"In January in the Kamituga area of South Kivu Province, Mai Mai leader Silvestre Louetcha reportedly executed 32 women who had supported the mwami [traditional ruler] of Kamituga in resisting Mai Mai demands for forced labor," notes a recent U.S. State Department report on human rights in the Congo. "Before killing these women, the Mai Mai reportedly accused them of witchcraft, then cut their breasts off and forced them to eat their own breasts ... There were also reports that Mai Mai units killed persons by crucifying them."

Such savagery is hauntingly echoed in another report:

"We fell upon them all and killed them without mercy ... [Our leader] ordered us to cut off the heads of the men and hang them on the village palisades, also their sexual members, and to hang the women and children on the palisades in the form of a cross."

Yet this last dispatch was written a century ago, by a European officer massacring Congolese villagers in the service of Belgium's King Leopold II, the most despotic of Africa's colonizers. Far from reverting to ancient tribal violence, Congo's modern combatants are simply updating the bloody colonial quest for rubber and ivory. Back then, as today, such horrors were kept secret. But the Congo remembers. Few countries are as scarred by their history.

"South Africa's turn to democracy may be the biggest success story in Africa since the Cold War," said Jakkie Potgieter, an expert with South Africa's Institute for Security Studies in Pretoria. "But the Congo is our biggest failure. You've got this rich, gigantic country in the middle of the continent that's sucking the whole region into disaster. If it drags on much longer, there really is no pulling back. It becomes another Angola."