The mob was organized by President Joseph Mobutu’s Mouvement Populaire Revolutionnaire, the only legal political party in the Congo. Outside the Belgian embassy in Kinshasa, it began to work up quite a head of steam for its "spontaneous anti-imperialist demonstration." Primary object was to protest the seven-week-old rebellion of the Congo’s white mercenaries, who were fired by Mobutu and subsequently captured the border city of Bukavu by force. Loudspeaker trucks promised immediate satisfaction to all loyal Congolese right there in Kinshasa. Before the shouting was over, announced the sound trucks, the Belgian, French and British ambassadors would be arrested.

The police had no intention of arresting the white diplomats, but even so the demonstration soon turned violent.

Led by thugs from the party’s far-left Jeunesse (youth) movement, some 2,000 Congolese stormed and sacked two floors of the Belgian embassy, invaded an adjacent apartment building and mauled an American Army sergeant and his wife who were trapped inside. Then it moved on to hurl rocks at the French cultural center and the American and British embassies, loot shops and set fire to cars along the way. Before Mobutu decided that it was time for him to ask the rioters to go home, they had torn down a 35-ft.-high bronze statue of Belgium’s King Albert I that had been a city landmark for years.

Party Ultimatum. In Brussels, the reaction was angry and immediate. Fearful that another anti-white bloodletting was imminent, Foreign Minister Pierre Harmel flew home from a vacation in southern France to appear on radio and television and demand that Mobutu guarantee the safety of the 40,000 Belgians who live in the Congo. Otherwise, Harmel implied, Belgium would cut off its $70 million-a-year aid program and order its citizens home, a move that could mean the virtual collapse of all the Congo’s industries, communications and civil service.

Despite the economic ruin that would follow a massive Belgian withdrawal, Mobutu was anything but contrite. He denied personal responsibility for the rioting, insisted that all well-meaning whites were perfectly safe in his country. If there was any anti-Belgian hysteria, he said, it was all to be blamed on the mercenaries sitting boldly in Bukavu and issuing ultimatums calling for the return of Moise Tshombe.

Even more unsettling, though, was an ultimatum issued by Mobutu’s own party headquarters, presumably with presidential approval. Unless the mercenaries evacuated Bukavu within ten days, it said, "all those supporting them will be spectacularly punished." In Congolese terms, that could be taken to mean death to all whites.

Source: https://content.time.com/time/subscriber/article/0,33009,841037,00.html