The Tutsis of this isolated border region of eastern Congo rose up in a rebellion early last October, backed by the armies of at least four neighboring African countries. Within eight months, the uprising that erupted in this backwater along the northern shores of Lake Tanganyika captured a mineral-rich country twice the size of Texas and toppled one of the most corrupt regimes of the late 20th century.

The swift campaign, in which rebel troops sped through vast territory famed for impassable roads and impenetrable jungles, pitted a disciplined David against a degenerate Goliath -- the regime of President Mobutu Sese Seku -- which crumbled as soon as it was pushed. Because it unrolled mainly through hostile forests far from transport and communications -- and because rebel leaders prevented reporters from accompanying them -- this extraordinary military feat was only sketchily described as it engulfed what was then known as Zaire last winter and spring.

Now, six weeks after the ailing Mobutu fled into exile and rebel leader Laurent Kabila installed his new government in Kinshasa and renamed the country, interviews with a broad range of rebel fighters, their enemies in Mobutu's army, international aid workers and Congolese civilians who witnessed the fighting have provided a clearer picture.

Their accounts show that the fight against Mobutu was bloodier than previously reported. In the first key weeks, more than 9,000 people -- mostly civilians -- are believed to have died in battles in the east of the country from Uvira to Goma, according to Congolese and U.N. officials who supervised the burial of the dead. Thousands more have died since, many of them Hutu refugees from neighboring Rwanda gunned down by rebel troops, some of them also Rwandan, under Kabila's nominal command.

The accounts also indicate that from the outset the rebels targeted the Hutu refugees, who fled Rwanda in 1994 after their leaders launched genocidal attacks against Tutsis there. An estimated 500,000 Tutsis, an ethnic group spread across several central African countries, died in the Rwandan bloodbath. But the killing ended with a victory by Rwandan Tutsis, who gained power in Kigali, the Rwandan capital -- along with a thirst for revenge.

Rwanda, Uganda and Burundi backed the war in Congo to avenge the 1994 genocide and to ensure that it does not happen again, rebel commanders said. Angola, Congo's western neighbor, later sent troops as well. Its political and military participation helped transform the war from a limited, border-clearing operation to a campaign to overthrow Mobutu's government in Kinshasa. Western diplomats and U.N. officials are split on whether rebel troops actually received orders to massacre the Rwandan Hutus in Congo. However, a number of sources said one of the main aims of the rebel offensive at the beginning was to force the Hutu refugees from the camps they had occupied for the previous two years near the Rwandan border. Also, the systematic way the killings happened -- in Mbandaka, in western Congo; near Kisangani in its center; and around Goma and Bukavu in the east -- have led U.N. investigators to conclude that the tragedy that befell thousands of Hutu refugees was no accident.

One Rwandan army colonel, interviewed in Goma, said his men came into this country for two reasons: to take revenge against the Hutu refugees and to ensure the security of Rwanda, which they saw as being threatened by the Hutu militants still in the camps. A senior Tutsi official in Congo's Interior Ministry, speaking in Kinshasa, said Rwandan troops and their Congolese Tutsi allies were given a free hand to go after the Hutu refugees so long as they also contributed to toppling Mobutu.

Rebel officers who opposed this policy were done away with. One, Andre Kisase Ngandu, a senior commander, was gunned down by Rwandan Tutsi troops near Goma on Jan. 6, a senior non-Tutsi rebel officer and other sources said.

The speed with which the rebel Democratic Forces for the Liberation of Congo-Zaire -- and Kabila -- took power meant that Kabila had no time to forge an identity for the fractious movement or a power base for himself. He did not participate in much of the planning or execution of the fight against Mobutu, Western diplomats said, and as a result, started his presidency more figurehead than chief.

It is still unclear who masterminded the rebel victory. The Congolese government has identified a Congolese, Gen. Nindaga Masasu, as the top commander of Kabila's troops. But African and Western military officers in Congo say another officer directed the campaign and has told Western military experts he is the chief of Kabila's army. He is James Kabari, described as a Tutsi of uncertain nationality who speaks broken English and fluent Swahili, two languages used in Uganda, and who knows neither French nor Lingala, the main Congolese tongues.

The actual rebel fighting forces were few in number, beginning the offensive with only 2,500 armed men. They were lightly equipped, with AK-47 assault rifles, shoulder-launched rocket-propelled grenades and small-bore mortars. Using canoes and on foot, they crisscrossed the country.

Mobutu's security services and army, on the other hand, were comparatively well supplied -- on paper. The military boasted 59,100 men with at least 40 tanks, 30 multiple-rocket launchers and 50 artillery pieces and even fielded two Soviet-made MI-24 helicopter gunships. But most of the army's equipment did not work; the helicopters, flown by mercenaries, got off the ground only a few times.

The pretext for the initial uprising here was an order issued last Oct. 7 by the Mobutu government giving Tutsis 72 hours to leave the country. In reality, the revolt had broken out three days before. On Oct. 4, rebel troops who had crossed the Ruzizi River from Rwanda struck a hospital and a Congolese army base near Lemera, a village on the Ruzizi plain between Lake Kivu and Lake Tanganyika. Within hours, the lieutenant colonel commanding the base was killed and government soldiers fled south toward Uvira.

The assault on Lemera followed a formula that proved successful throughout the later fighting. The rebels attacked from several directions simultaneously, confusing Mobutu's troops but leaving them an escape route. They infiltrated their men inside the village before they struck. They kicked off the assault by dropping a mortar shell into the middle of the Congolese army base. And they used walkie-talkies to coordinate their actions.

As the government troops fled south to Uvira, other patterns developed that recurred throughout the war. The soldiers, many of whom had not been paid their monthly $1 wage in a year, began to loot stores and houses. The fleeing government army came to the Fizi region, inhabited by the Bembe tribe, long an enemy of the Tutsis. But the Bembe killed scores of the fleeing soldiers because they had pillaged Bembe villages.

"The support of the people" is how Paul Kabongo, Congo's current security chief, explained the rebels' swift victory. "The army was a fish in a sea of the people."

Uvira fell on Oct. 24. The rebel troops treated local residents well, but Hutu refugees were separated from the returning crowd, and many of them were killed. In Uvira, Baudouin Mibenge, a grocer, said he saw hundreds of bodies in the streets, on the port and floating in the choppy, blue waters of Lake Tanganyika. Among the dead were many women and children. Red Cross officials said they buried more than 1,600 corpses in Uvira that month.

On Nov. 1, Kabila, a small-time Marxist revolutionary who had enriched himself selling Congolese gold, emerged in Uvira as the representative of an organization named the Alliance of Democratic Forces for the Liberation of Congo-Zaire. In the beginning Kabila was identified as the spokesman. Soon Kabila began calling himself the leader.

Rebel commanders explained that Kabila, 56, who had been fighting against Mobutu since 1963, was a convenient choice. He had good relations with Rwanda, Uganda and an important rebel faction, the Banyamulenge of South Kivu Province, a group of Congolese Tutsis who constituted some of the rebels' most successful forces. But he himself was a Luba, not a Tutsi, and thus more palatable to Congo's 400 other tribes.

Kabila had little or no role in planning and executing the war, according to Western military observers and Tutsi officers from Rwanda and Congo. And his son, Joseph, who has been identified by some press reports as a senior commander, is today an aide to Kabari at the Defense Ministry.

By Oct. 30, the troops who had taken Uvira were in Bukavu, 100 miles up the road from Uvira on the south shore of Lake Kivu. Rwandan, Ugandan and Burundian regulars were pouring across the border at Ruzizi, south of Bukavu, and from the Cynagugu crossing in Rwanda, swelling rebel strength to about 1,700 men. Several Rwandan officers among the rebels said in interviews that the officer corps was dominated by Rwandans. The foot soldiers were mixed.

From the outset, the main rebel targets in this southern campaign were U.N.-protected refugee camps. The rebels mauled camps along the road from Uvira to Bukavu; they attacked the Inera and Kashucha camps north of Bukavu, where the United Nations had allowed the radical Hutu leadership to house its government in exile since 1994. More than 120,000 people had lived there.

On the day Uvira fell, about 700 rebel troops opened another front, sneaking into Congo about 25 miles north of Goma, on the north shore of Lake Kivu. They struck first at the Kibumba refugee camp, which housed 200,000 Hutus.

Mobutu's Presidential Guard, backed by Hutu militiamen, defended the camp and suffered heavy casualties, according to Mike Deppner, a Canadian doctor who works for the U.N. High Commissioner for Refugees. When Deppner returned to the camp in November, he said, he found dozens of bodies stuffed in outdoor latrines and 40 lying in the camp's hospital with intravenous tubes still in their arms.

Most of Kibumba's 200,000 refugees fled toward Goma, finding shelter next to another massive camp, Mugunga, west of Goma. In all, more than 500,000 refugees huddled near the lakeside town. Goma fell Nov. 1. Attacked from the north, from the east out of Rwanda and from the lake, where Rwandan gunboats peppered the city with shells, Mobutu's defenses collapsed quickly. At least 6,800 bodies later were buried near the town, said Craig Sanders, a senior U.N. aid official there.

November was a critical time for the rebels. Talk was rife in Western capitals, particularly in Canada, of dispatching an international force to save the Hutu refugees, an outcome that could have grounded the fledgling revolt. On Nov. 15, Kabari's forces solved that problem. They attacked the Mugunga camp.

Kabari gave the order to strike Mugunga from the west, giving the refugees one escape route -- east, back home to Rwanda. That assault began one of the largest spontaneous repatriations in recent history. But, just as significantly for the rebels, it also ended any talk of an international force for Congo. Between Nov. 15 and 19, about 600,000 Rwandan Hutu refugees flooded home -- half the number that had fled in 1994.

Still, tens of thousands of other Hutu refugees were driven deeper into the Congolese jungle. The rebels pursued them, killing as they went.

Meanwhile, the government's defenses were collapsing.

Capt. Kopla Masitolo was a commando in Mobutu's army, fresh from eight years of training in Egypt. He was based in Bunia, an important crossroads in northeastern Congo, 225 miles north of Goma, deep into a province then called Upper Zaire. By mid-December, Rwandan, Ugandan and rebel troops had neared the town and were preparing an attack. Mobutu dispatched the 31st Paratroop Brigade, one of the country's elite units, to help defend it. The paratroops, backed by other government regulars, had bottled up the rebels.

Then ammunition ran out, Masitolo said. "We called and called Kinshasa, but nothing came." Bunia fell on Christmas Eve. Within weeks the 31st Paratroops had switched sides.

With eastern Congo captured, the rebel factions began bickering.

The Rwandans and the Ugandans saw the rebellion as an opportunity to clean up the border area, create a buffer zone and stop there, one U.S. official explained. But Angola's government, eager to topple Mobutu because he had helped, and was still helping, Angola's UNITA rebels headed by Jonas Savimbi, magnified the ambitions of the rebels -- to take Kinshasa as well.

By mid-February, the Angolans had prevailed and the push continued. Rebels moved west from Bunia, and northwest, west and south from Bukavu. Large numbers of Katangese troops led by Angolan officers began arriving at Bukavu's airport from Angola. Later, more Angolans entered by land from the south.

Mobutu's army concentrated on defending Kisangani, the place where his forces would launch what was advertised as "the great lightning counteroffensive." Military experts in Kinshasa and other capitals pointed to the looming battle as the one that would decide the war. But when he arrived at the town after fleeing 320 miles from Bunia, Masitolo said, he found little lightning. Instead, five senior officers were competing over who would lead the counterattack.

Reinforcements arrived from Kinshasa, but they brought no food. When food did arrive -- in one case, a planeload of fish -- the cooking crew sold it. Guns were delivered but not bullets. Serb mercenaries, infamous for their brutality in the Bosnian war, terrorized the local population, reports said.

The attack on Kisangani began March 13 at Babagulu, a dusty hamlet of mud huts and cassava fields 36 miles east of the riverside target town. Local villagers led the rebels through the forest so they could outflank the government troops and fire on them from three sides.

"It wasn't a fair fight," said a 22-year-old fighter still stationed in the village. "We hid in the jungle, fired onto the road and wiped them out."

Kisangani fell on March 15. With northern Congo firmly in rebel hands, combat shifted to the south.

The rebels' tactics also changed. Success allowed the rebels to quicken their pace and open a front hundreds of miles wide. An advance guard, a group of 300 Rwandan and Banyamulenge troops, would seize a town and leave the mop-up for the rebels' rear guard. The tactic was risky, but the results were tremendous.

From November to March, the fighters had seized one-third of Congo. By the end of April, just one month later, two-thirds of the country was in their hands.

On April 6, peace talks began in South Africa. Although a cease-fire had been declared, rebel troops used the hiatus to prepare for another southern assault. It came three days later, on April 9, when a column of 300 men took the key mining town of Lubumbashi with no heavy weapons. Neighboring Zambia granted the rebels free passage so Lubumbashi was easily surrounded.

Other towns fell in rapid succession. On the last day of April, rebel forces seized Kikwit, more than 600 miles through thick jungle from where they started on March 1.

Mobutu's last stand occurred on a bridge over the Bombo River, 60 miles east of Kinshasa, on May 15. The army chief, Gen. Marc Mahele Lieko Bokungu, had constructed what he claimed would be "a wall of steel" against the rebel troops. Mahele dynamited the bridge and ordered his troops to dig in on the steep western banks of the 60-foot-wide river.

But 500 rebels already had sneaked across the river's black waters, outflanking the capital's defenders. The government army fled. The next day, Mobutu flew out of Kinshasa after Mahele informed his president that he would fight no more. A Mobutu loyalist shot Mahele to death in the presidential palace that day.

At 2 a.m. on May 17, rebel patrols entered the capital, trudging into Kinshasa along its rusting railroad tracks.

CAPTION: Refugees, above, awaited transport to Rwanda last November after fleeing camps in eastern Congo.

CAPTION: At left, rebels celebrated in Goma last February after capturing the town.

CAPTION: Civilians returned to Bukavu, Congo, after fierce fighting last November as a Red Cross worker stood by. Congolese rebels attacked refugee camps in the area.