But most of Kinshasa’s 5 million people welcomed the rebels with praise and thanksgiving. As the first columns strutted into town from the airport, singing their marching songs, there was little violence. Far behind his own front lines, the new rul er of Zaire issued a statement grandly referring to himself in the third person: ““Mr. Laurent Desire Kabila assumes from today the functions of the head of state of the Democratic Republic of the Congo.''

Apart from changing the country’s name back to its pre-Mobutu roots, Kabila gave little indication of what he would do with his stunningly swift victory, which took him from obscurity in the eastern hills clear across an immense country in just sev en months. A onetime Marxist revolutionary and enterprising gold smuggler, Kabila was a triumphant enigma. He said he would form a ““government of national salvation’’ within 72 hours and a new constituent assembly in 60 days. He promised to hold free el ections, but he didn’t say when. Kabila also said he had spoken by telephone to Mobutu’s generals, and they were ““ready to receive orders from me.''

Who, if anyone, would give orders to Kabila? His supporters hailed him as another African strongman; others called him a figurehead for a multitude of foreign forces and domestic factions. Unlike Kabila, many of his fighters were Zairean Tutsis. Hi s rebel alliance had been sponsored by other African countries, notably Angola, Uganda and Rwanda, with patronage from sources as far away as Europe and the United States. His advisers talked about building a constitution and a police force on U.S. model s and making English a second official language, along with French. For the moment, however, all Kabila had to do was savor his victory. ““I am happy, very happy to succeed,’’ he told reporters.

That ended Mobutu’s reign of nearly 32 years as Zaire’s president, tyrant and looter in chief. His country was impoverished and in ruins, its backwoods still occupied by hundreds of thousands of Rwandan Hutu refugees, their condition increasingly d esperate. His own body riddled with terminal cancer, Mobutu, 66, finally gave up power and went into exile, flying with his family in three planes to Morocco. From there, it was expected he would go on to France. {BN****EN}He was rumored to have a mu ltibillion-dollar fortune, but it wasn’t clear where he had stashed it. Switzerland, one likely depository, froze all his assets there last week.

Washington had propped up Mobutu for years and got good use from him in the cold war’s African sideshows, but cut him off in the late ’80s. Now, in an article written for NEWSWEEK (sidebar), Bill Richardson, President Clinton’s special envoy to the region, signals that America is willing to do business with Kabila’s new government - providing he manages to behave better than Mobutu ever did.

As the rebel army closed in on Kinshasa, South African President Nelson Mandela failed in a last-ditch effort to mediate a peaceful settlement. Many people thought the result would be a bloodbath in Kinshasa, requiring intervention by Western troop s waiting across the river in Brazzaville. According to the State Depart-ment, 325 American civilians were still in the country, and spokesman Nicholas Burns offered them this advice: ““Get out of Zaire before you find yourself in harm’s way.’’ Poised to rescue the 200 Americans in Kinshasa were 300 U.S. troops in Brazzaville and 1,050 more marines aboard the assault ship Kearsarge, positioned on Simba Station off the Zairean coast. But by the end of the week, Opera- tion Guardian Retrieval was still on hold.

Most of Kinshasa had been carefully prepared for the rebels’ arrival - and the disgruntled departure of Mobutu’s forces. At the city’s university, a small, experimental nuclear reactor was under heavy guard. ““If some crazy group blew it up,’’ said the head of the physics department, ““there would be a cloud of radioactive dust which could kill people.’’ Most of Mobutu’s high-ranking supporters were only interested in getting out of the country. They took their families to the Hotel Inter-Continen tal, a way station on the route to the beach. There were occasional gunshots and explosions, plus reports of sporadic looting, but by Saturday night the rebels were on Kinshasa radio warning everyone to stay calm.

Potentially the most dangerous holdouts were the fighters of the DSP, many drawn from Mobutu’s own tribe. Tough and well armed, they were holed up in their bastion at Camp Tshatshi, next to Mobutu’s palace. At first, one of the officers with them was Mobutu Kongolo, the dictator’s son, a hothead known locally as ““Saddam Hussein.’’ Unconfirmed rumors said he was the soldier who shot the defense minister. But on Saturday the younger Mobutu finally slipped away. He was seen landing in Brazzaville, accompanied by two Westerners, according to one source.

Laurent Kabila was not expected to reach the capital until this week at the earliest. It may be weeks more before it becomes clear how much political opposition he will tolerate, or from where his strongest support comes. Militarily, his forces appear to be split between ethnic Tutsis, supported by Uganda and Rwanda, and fighters from Kasai and Shaba provinces in the south, supported by Angola. Kabila’s civilian apparatus may also split into factions. One political grouping, called the Convention of Communities, claims overlapping membership with the rebel alliance and has used exiles in Belgium and Luxembourg to plan a new government and build links to Western powers. But is Kabila capable of governing a huge, disparate and devastated country? F or more than 30 years he has been a revolutionary and a warlord, but not yet a statesman. He has promised to hold free elections and encourage foreign investment. So, of course, did Mobutu. Pray that Kabila does not become the kind of ruler he struggled for so long to overthrow.