They are called the "comrades," and in this year of struggle, burning and death they have emerged as the young foot soldiers of a largely leaderless, faceless movement that has challenged the power of Africa's last white bastion.

In their angry passion, their certainty and their self-destructiveness, young urban blacks have set their own communities aflame -- but they have also plunged white South Africa into its most severe political and financial crisis since the Boer War of 1899.

Aided by a government whose police tactics consistently have undercut its expressed desire for "reform," they have succeeded in sustaining 16 months of civil unrest. They have discredited Pretoria's strategy of limited change, damaged its economy and done permanent harm to its standing abroad.

Unrest has spread from traditional urban flashpoints like Soweto, Port Elizabeth and Cape Town, into townships and rural areas once noted for their tranquility and conservatism. In the process, blacks have revived and refined economic weapons such as consumer boycotts that have jolted segments of the white community in a way they never had been touched before.

The unrest also has helped revive the standing of the organization with which many blacks identify most closely, the outlawed African National Congress. The United Democratic Front, the internal political movement that most nearly reflects the congress' concept of a future South Africa, survived a year of harsh repression.

At the same time, many black moderates have found themselves trapped between their often radicalized children and a police force many of them see as brutal and unyielding.

The political middle ground has all but vanished. Those who have been perceived as cooperating in any way with the white authorities have lost credibility, support and, in some cases, their lives.

Still, while blacks have succeeded for the first time in a generation in seriously damaging white South Africa, they remain far from their goal of toppling white rule. The dream that many youths believe is around the corner remains elusive. And because white military power remains intact, there is no clear path to get there. Blacks have created an enduring crisis, not a revolution.

"We have tested the regime to some extent, but we have failed to realize our potential," said the Rev. Joe Seoka, an Anglican cleric and deputy president of the Azanian People's Organization, a radical group whose Black Consciousness philosophy sets it apart from the multiracial stance of the ANC and the UDF.

"It is worrying to us," said a young activist, known as Lucas, in Crossroads, the bleak squatter community outside Cape Town that has been the scene of periodic spasms of violence and police roundups for the past year.

"The power of the people is very strong, but we lack the means of confronting the regime. The regime is the one that does the shooting and the people do the dying."

To a great extent, Lucas and his fellow "comrades" have become the heart and soul of the challenge to white rule, and there are groups who identify themselves as "comrades" in virtually every major black urban center. Through inspiration and intimidation -- and, on occasion, through public killings -- they have compelled fellow blacks, many of whom already support their goals, to acquiesce in their tactics.

The "comrades" are a mixed bag of militants, street thugs and bored teen-agers. In black communities like Soweto and Crossroads, many come from the long-organized network of street gangs that operate like little mafias among the squalor and the poverty of the townships. Elsewhere they are groups that have spontaneously risen from early episodes of unrest. Massive unemployment among young blacks -- it excering with some of his work. inferiority of South Africa's segregated black schools.

Their politics, as suggested by the name they have chosen for themselves, is often an amorphous blend of vague socialism, black nationalism and, increasingly, anti-Americanism. But mostly they define themselves by their enemy -- the "system" in all its hated manifestations: the schools, police, soldiers and those blacks who "collaborate" by working for the government and its various agencies. The "Necklace" Becomes a Symbol

Those who defy the will of the comrades face retribution. Shoppers who buy goods from boycotted white stores have been forced to drink liquid detergent or eat raw meat. A 20-year-old man was stoned and then burned to death in Soweto two weeks ago for holding a house party in violation of a "people's ban" on Christmastime festivities. A young student nurse accused of breaking a strike at a Soweto hospital last month was set ablaze.

The "necklace" -- a tire filled with gasoline, placed around the neck of a "traitor" and set on fire -- has become the macabre symbol of a generation that believes it has nothing to lose. Of the nearly 1,000 blacks who have died since the unrest began in September 1984, almost one-third have been killed by other blacks, with most of the remainder shot by police or soldiers.

"We have gained the power," said Scipho, a teen-aged activist in Crossroads. "Everybody now is prepared to die for his rights. People no longer feel threatened by the bullets. When they see soldiers and police they are eager to confront them. They the government have arrested our leaders but the situation just goes from bad to worse."

Consumer boycotts of white businesses have been a key element in the rise of black power in perhaps a dozen urban areas. In areas like eastern Cape Province, boycotts forced the white business community to intercede with the government for the release of local black leaders and for the withdrawal of the Army from black townships.

While organized by community groups linked to the United Democratic Front, the boycotts have been most effective when enforced by the comrades, often operating with the tacit consent of UDF leaders. In many townships the comrades have used the boycotts to consolidate their own hold.

A year ago, Mamelodi, a black satellite town on the outskirts of Pretoria, the seat of white rule, was a quiet, model community with a well-defined and compliant black power structure. Today it is under the de facto control of the comrades.

School boycott committees decide when children go to school and when they stay home. A business boycott committee determines when and where people shop. A "people's court" even decides, in some cases, who lives and who dies.

The government lost control of Mamelodi through a now familiar combination of black grievances and police repression. A school boycott organized by the UDF-affiliated Congress of South African Students turned into a running street battle between stone-throwing youths and armed police when authorities tried to force students back to the classrooms. A black policeman was killed. Some children died and others were beaten by black police, who seemed to residents to be out of control.

Adults who intervened found themselves under assault. The car of Louis Khumalo, a pharmacist who organized a parents' association, was blown up last May. In October he was detained without charge for a week. Last month, Khumalo said, he was clubbed repeatedly by a black police lieutenant on a Mamelodi street and later arrested and beaten while in custody by police who accused him of instigating unrest. Last week he was detained once more, along with the president of the town's chamber of commerce and five other businessmen and clerics, accused of helping to organize a boycott of white businesses.

The bitterness and the alienation came to a head Nov. 21 when a peaceful protest rally of nearly 50,000 residents outsidering with some of his work. police opened fire with shotguns and tear gas. At least 13 blacks died. The radicalization of Mamelodi was complete.

What happened in Mamelodi has been repeated in variations throughout South Africa's urban townships. It has been a process of alienation and polarization. Black youths, said the Rev. Nico Smith, a sympathetic, white Dutch Reformed minister who lives on the outskirts of Mamelodi and leads a black congregation there, have "lost their sensitivity for life. They have reached the point of no hope."

Smith recalled a recent meeting he had with some of the comrades in which he argued that they should return to school because, as he put it, "education is power.

"They said it indicated how little I knew," said Smith. One youth described how his father, a high school principal with two university degrees, had been stopped at a police roadblock and hauled off to jail in front of his son because he had left at home his "pass," the identity book that all urban blacks are required to carry. The lesson, the youth told Smith, was that "even the most educated black man is treated like dirt -- the schools are there to make us better trained slaves."

In this charged and bitter atmosphere, the ties binding parents and children have been tested and strained. If they hold, it is often because the parents recognize in their children the same discontent they carry in themselves.

"Young people are driven by the same anger and frustration that I feel," said Zodwa Mabaso, a UDF supporter and Soweto mother of four who spent four months without charge in detention last year. "But they are more bitter. I can still feel sorry for the policeman, but that's not the same for young people.

"Our children are no longer children. They become adults and we ourselves become the children. Even a 10-year-old will tell you there's no time for play and no time for school, only time to think about what you do if the policemanring with some of his work. townships in the region.

The pattern was set. From then on, as the unrest spread from town to town, the targets almost always included blacks identified with "the system." Black policemen, town councilmen, alleged police informers -- all were singled out, their houses burned, their shops looted, their lives put at risk.

The idea, as a young activist in the East Rand township of KwaThema put it, was to make them "feel the same pain that we are feeling." The effect was to undermine and wreck the incipient deal South Africa's white rulers had hoped to forge with an urban black middle class.

Perhaps the biggest winner in the unrest is an organization that had little role in initiating it -- the African National Congress.

Leaders of the congress have been in jail or exile since the organization was outlawed in 1960 after the Sharpeville Massacre. The low-level sabotage campaign they have been waging against the government seemed to reach a dead end in early 1984 when South Africa signed a nonaggression pact with Mozambique, the black Marxist state that had provided the main springboard for ANC attacks. With its main operatives expelled from Maputo and with President Pieter W. Botha received as a reformer on his June tour of Europe, the ANC appeared to retreat into a sullen shell. Devotion to the ANC

But even at its lowest moment, the ANC had a crucial weapon in its depleted armory -- black devotion. Many looked to it as the only organization willing to mount a military challenge, however small or ineffective, against white rule. Older blacks based their loyalty on the memory of the organization's mass protests in the 1950s, while the young idealized a movement they had never seen and leaders they had never heard.

"Where are you, Oliver Tambo?" go the words to one of the many freedom songs that resound at funerals for victims of the violence. It goes on to plead with the ANC leader for machine guns and bazookas to kill white soldiers. "We are waiting for you to lead us to freedom."

The congress was quick to react to the unrest with calls for youths to attack "enemy personnel" and render the black townships "ungovernable." In some areas, mostly around Cape Province, the ANC's traditional stronghold, congress operatives have played a major role in planning attacks on policemen and organizing actions such as boycotts.

Elsewhere its role has been mostly inspirational, its calls for insurrection usually at least one step behind events. Recent South African visitors to Lusaka, white businessmen and liberal politicians, have come away with the impression that the ANC's leadership fears that the anarchy on township streets is out of its control.

There are at least two contrasting sides to the ANC as seen from South Africa, and the organization is considered to have alternated smoothly between them this year.

The side the businessmen saw in Lusaka is that of moderation and reasonableness. It is the same one Oliver Tambo presented to Cape Times editor Anthony Heard in the interview Heard published here in November in defiance of South African law.

Tambo stressed the movement's hopes for a nonracial South Africa where "everybody's property is secure." Violence could be suspended and negotiations with the government could begin, he said, as soon as Pretoria demonstrates its readiness by releasing imprisoned ANC leader Nelson Mandela and other political prisoners, lifting the state of emergency, pulling troops out of the townships and ending the ban on the ANC.

"There is always the possibility of a truce," said Tambo. "It would be very, very easy if, for example, we started negotiations."

Those deftly worded statements have helped to drive a new wedge into the once rock-solid white community here and to nurture doubts among some whites about their government's ironclad refusal to release Mandela or talk to the ANC until it denounces violence, cuts all ties to Communists and submits, in Botha's words, to "constitutional means." ANC's Violent Side

The other side of the ANC is more radical and more violent. Its voice can be heard on Radio Freedom, broadcast from Ethiopia, Tanzania and Zambia, urging blacks not only to "eliminate enemy agents within our community," but to take the struggle into white suburbs. "Let them feel that the country is at war," instructed an Aug. 2 broadcast from Addis Ababa. Other broadcasts encouraged black maids to attack the homes of their white employers.

The ANC's military wing has dramatically stepped up the number of its attacks inside South Africa this past year -- 122 as of Dec. 15 compared to only 44 for all of 1984, according to the Institute of Strategic Studies at the University of Pretoria. Among them was the recent land-mine explosion that took the lives of six white women and children in a northern farming community near the Zimbabwean border.

Such attacks are too infrequent to terrorize the white community into submission or to do major economic damage. They tend instead to have the opposite effect -- uniting whites behind retaliatory raids into neighboring states and the government's no-talks policy.

Among blacks, however, the attacks are widely applauded as one of the few ways whites can be made to feel some of the same despair that permeates the townships. "There is a greater respect for the ANC," says Lucas, the young Crossroads activist. "Wherever you hear the word ANC, people listen."

There is evidence that even blacks in more conservative rural areas believe the violence is justified in fighting white rule. A recent survey of 120 school teachers and civil servants in Lebowa, a nonindependent "homeland" in the northern Transvaal, found that 78 percent approved of student boycotts and other actions even when they lead to violence.

"Even damage to buildings, injuries to people and other forms of physical violence are mostly described as the inevitable consequence of apartheid," wrote Johan Malan, a white anthropologist who conducted the survey. "The general contention is that if less boycotts and violence occur, the government will not be embarrassed enough to consider the dismantling of apartheid."

The Soviet Bloc provides the ANC with most of its military hardware, and analysts estimate there are about a dozen members of the small South African Communist Party on the ANC's 30-member National Executive Council. But Tambo, himself a noncommunist, centrist figure, has been careful to keep the movement broad-based and flexible, emphasizing his pragmatism to western governments and businessmen at events such as the private dinner he held with American corporate leaders in New York earlier this year.

Again, the politically moderate tones of Tambo contrast with the strident Marxism displayed by such information organs as Sechaba, the ANC's monthly magazine published in East Germany. As the struggle continues and Tambo and other older nationalists are replaced, many analysts believe the congress inevitably will shift farther to the left.

While the ANC has gained stature this year, political moderates identified to any extent with the government have been the biggest losers. The Labor Party, once the foremost political movement of mixed-race or Colored South Africans, is widely believed to have lost much of its urban constituency because of its participation in the new constitution's tricameral Parliament.

When Colored students in Cape Town stepped up a series of school boycotts in September, the party's minister of education closed the schools for nearly a month and fired dozens of activist teachers. As a result, the party has been more closely identified with the government it once bitterly opposed.

Similarly, Zulu Chief Buthelezi, whom many white moderates see as the black leader they can most readily bargain with, found himself at war with the ANC and supporters of the United Democratic Front, who accused him of being a "puppet" of the government.

Buthelezi preaches nonviolence, but members of his Inkatha cultural movement formed vigilante committees and participated in the factional fighting that rocked Durban's townships in August with at least 70 deaths. The Zulu groups, armed with traditional clubs and spears, operated with the tacit consent of white police, who stood aside while they restored "order."

His critics contend that Buthelezi someday will be enticed into playing the same collaborationist role that Methodist Bishop Abel Muzorewa played in preindependence Zimbabwe. But Buthelezi has held back, strongly criticizing the Botha government and refusing to be seen negotiating until a minimum set of conditions, including the release of Mandela, is met.

He is seen as more likely to end up in the same role as another Zimbabwean nationalist, Joshua Nkomo, who could not expand his strong regional following into a national power base.

Even white liberals have begun to have second thoughts about Buthelezi. The trips to Lusaka to meet the ANC, the arch-rival of Buthelezi's Inkatha organization, were considered a blow to the chief's stature. So too was the failure of a much publicized alliance for a national constitutional convention launched by Buthelezi and the white Progressive Federal Party.

The movement failed to enlist black support outside Inkatha after the ANC reportedly sent word that it believed the alliance "premature." Buthelezi's supporters eventually resigned from the steering committee of the alliance, which is still searching for black moderates.

The failure of the movement was another indication of how thin the political middle ground has become here for both whites and blacks. It also illustrated the control the ANC can wield.

But while the ANC-UDF phalanx may be ascendant, blacks are still far from united. The battles between the UDF and Buthelezi, between the UDF and supporters of Black Consciousness, and the endless search for "traitors" and "collaborators" have had a corrosring with some of his work.