In predawn raids on Dec. 5, 1956, South African police began the round-up of 156 Africans, whites, Indians and Coloreds on charges of high treason. Thus began one of the most spectacular political trials since the burning of the Reichstag in Berlin in 1933. Hundreds of trials have taken place in the 25 years since. The extraparliamentary opposition has suffered setbacks through bannings, detention, jail and torture. Yet today leaders of the black majority are more confident than ever about liberation from white minority rule. Some of the most important are among those arrested in 1956.

The trial collapsed in March 1961 after the prosecution had failed to demonstrate that the African National Congress and its allies were "a country-wide conspiracy" inspired by international communism to overthrow the state by violence. The ANC had already been banned, however, and driven underground a year earlier in the Sharpeville crisis. By late 1961, after nearly a half-century as the voice of the voteless majority, it embarked on "armed struggle."

Among today's heroes are men and women who have died since they were on trial: in 1967 Chief Albert Lutuli, president-general of the ANC, a mildly socialist Christian democrat who won the Nobel Peace Prize; in 1968 Z. K. Matthews, the preeminent African academic of his time and, like Lutuli, an ANC leader and reputed "moderate" who believed no black could be a moderate in South Africa; in 1978 Dr. G. M. Naicker, the Natal Indian leader, a Gandhian; in the same year, Moses Kotane, an ANC activist since 1928 and secretary-general of the Communist Party before it was banned in 1950; and in 1980 Lilian Ngoyi, the outstanding women's leader, whose funeral was an outpouring of demands for liberation.

Black politics are complex, divisive and vulnerable to crippling action by the regime; understandably, there is a yearning for unity and action. In satisfying this, the ANC--historic and nondoctrinaire--has shown a dramatic resurgence in recent years, manifested not only by more sophisticated sabotage and guerrilla attacks but also in the courageous openness of popular support. The police say it is "everywhere."

The ANC also lends legitimacy. Thus visitors are informed that John Mavuso, prominent in the Inkatha movement of Chief Gatsha Buthelezi, head of the Zulu "homeland," was a member of the ANC's national executive before his arrest for treason. Inkatha itself identifies with the ANC's aim of a nonracial, undivided South Africa although it responds to conservative impulses and rejects armed struggle. It is on Robben Island off Cape Town that the heart of the ANC is to be found. There, Nelson Mandela, 63, Walter Sisulu, 69, and Govan Mbeki, 71, have been serving life sentences since 1964. (Mbeki was not arrested in 1956 but was indicted as a "co-conspirator.") As leaders of the ANC's nonracial military wing, they admitted planning sabotage and preparing for guerrilla warfare. With the resurgence of the ANC, most recently among black workers, Mandela's luster as a symbol of hope for liberation has brightened.

In August 1981, the Johannesburg Star reported that Mandela was "strongly" liked by 59 percent of blacks surveyed in Johannesburg, Cape Town and Durban. Comparable percentages were 32 for the pro-ANC Dr. Motlana of Soweto and 20 for Chief Buthelezi. Earlier in the year, Ton Vosloo, an influential National Party editor, described the ANC as "the National Party of Black Nationalism" with which the government would have to negotiate some day.

Such negotiations might include the sons and daughters of those tried for treason--for example, Thabo Mbeki, in exile, secretary for political affairs in the office of Oliver Tambo, 54, the president-general.

A few days before Tambo's arrest in 1956, the Anglican bishop of Johannesburg accepted him as a candidate for holy orders. He has seemed an unlikely leader of a armed struggle, but intensified repression have steeled his determination. He receives through the Organization of African Unity arms from the Soviet Union. Moral and financial support comes from Swedish, Danish, Norwegian and Dutch governments, democratic socialist parties and the World Council of Churches. Offices have recently opened in Bonn, Vienna and Brussels and will soon in Paris. In June, for the first time, representatives of major U.S. corporations and banks, hedging their bets, met with Tambo.

The Reagan State Department even at the junior level has no contact with the ANC. The unprecedented contacts of the Carter administration with a wide range of leaders have been dropped. Reagan policymakers believe they are realistic in basing their "constructive engagement" with South Africa on the ruling whites. As events unfold, can the United States afford to keep its head in the sand?