The armored troop carrier was treading its way through the crooked side streets of the black shantytown when the white soldiers spotted a suspicious-looking cluster of young blacks.

The group broke and scattered into the ghetto's back alleys, and the soldiers climbed down to give chase. In the excitement, a 19-year-old corporal named Johan Schoeman left his rifle in the vehicle.

He never came back for it. Schoeman's body, with 73 stab wounds, was found face down in an alley. Police believe that as many as 30 different persons participated in the slaying, which they say may have been a premeditated ambush.

Schoeman's killing Oct. 13 in KwaZakele, a township on the northern edge of this port city, was the first of a soldier during the past 14 months of black unrest in South Africa. It has fueled one of the most heated debates raging in this divided land -- the role of the Army in suppressing urban black rebellion.

Although officials refuse to release figures, it is clear that the military presence in black townships has increased sizably since 7,000 troops first were deployed a year ago during a search-and-seizure operation in the township of Sebokeng, south of Johannesburg.

If the violence continues to spiral, as many here expect, military involvement also will grow. Some officers already are arguing privately that the Army should take full responsibility for the enforcement of order in the townships, according to western diplomatic sources.

South Africa has universal conscription -- but for whites only. Draftees serve two years, then are subject to another 24 months' service spread out over a 12-year period. At any given time, the Army usually includes about 28,000 professional soldiers and 53,000 conscripts, according to the International Institute for Strategic Studies in London.

In contrast with the 45,000-man national police force, about half of which is nonwhite, the South African Army is virtually all white. The exceptions are small numbers of segregated, volunteer units of mixed-race or Indian soldiers.

The government says troops are necessary in the townships because the national police force has been spread thin by the amount and geographic diversity of the violence, which has claimed more than 750 lives since September 1984.

But critics contend that the government is misusing the Army for political purposes and is oblivious to the implications of deploying troops, many of them conscripts, against fellow South Africans. Army involvement also has given new momentum to the country's small but growing antidraft campaign and given black township residents a new grievance to rally around.

It is also said to have raised questions among some ranking military officers, arguing that their men are ill-suited for this unusual role and chafing at their subordinate position to the much criticized national police.

Officials will not discuss these matters publicly -- the Army, the police and the deputy Cabinet minister who oversees both of them turned down several requests for interviews. But through a number of recent gestures, including the opening of public complaint offices and the construction of sports fields in townships, the Army has sought to distance itself from the police in the minds of black residents.

Gen. Magnus Malan, the minister of defense, gave the official view in a recent interview with the Johannesburg Star. "The troops are asked every day not to leave the areas because the majority of people value and desire their protection," he said.

But the view looks very different from the townships. There, the soldiers are widely seen as a symbols of military occupation and of the government's determination to crush opposition. "There is no doubt that the presence of the Army -- representing a killing and fighting force -- causes psychological terror," said a recent report by Women for Peace, a liberal lobbying group that surveyed blacks.

Some of the most bitter resentment has been evident in Soweto, the country's largest black urban center, ever since the military participated in a mass roundup of allegedly boycotting schoolchildren two months ago. A meeting of parents and students organized by the Soweto Civic Association last week heard impassioned denunciations of the troops and claims that students could not walk Soweto's streets safely until the military pulls out.

"The soldiers must go back to the border where they belong," said one student leader to loud applause. "Until they leave, we will not go back to school."

The paradox is that township residents generally say the Army has acted less brutally than the police, who have been responsible for most of the killings of blacks by security forces this year. But the sight of armed and helmeted white men moving down their streets in heavy armored vehicles has become a constant reminder to residents of the state of emergency they live under.

"To us, the police and the soldiers are the same thing -- they are cooperating in all fields." said Emmanuel Dlali, a leader of the Port Elizabeth Youth Congress, a radical black community organization. "There is a need for some police, but the soldiers are trained for war and killing. They should not be here."

Reports of military misconduct appear to have increased along with the Army's presence. Two young conscripts were convicted last week of stealing a video recorder from a township home here. Two others have been accused of raping a black grandmother in the country town of Cradock.

In New Brighton, another township, soldiers guarding the post office allegedly used a nearby shop for target practice. There have been many other charges.

To combat such allegations, the Army opened more than two dozen offices early last month to receive complaints against soldiers. But they have received fewer than a half dozen complaints. Commandant Ian Buck, an Army spokesman, attributed the lack of complaints to "intimidation" by township radicals, while critics contend that blacks do not report because they have no faith in the Army's ability to police itself.

Like most armies, the South African Defense Force prides itself on discipline and training, and the written orders handed out to troops in this eastern Cape community include commands to "respect human dignity" and "avoid conflict." But those who have been involved say discipline often wears thin in the atmosphere of boredom and anxiety in which the troops operate in the townships.

A young conscript, in a letter describing his experiences, wrote that at first township patrol outside Port Elizabeth was "something of a joy-ride." Later, he said, it became "a bad dream."

The letter, written to Janet Cherry, eastern Cape chairman of the End Conscription Campaign, said discipline and respect for local residents were quickly eroded by boredom and by constant contact with the police, who often ride along with soldiers on patrols and whom he described as undisciplined and brutal.

"The majority of my peers are not afraid or confused," wrote the conscript, who Cherry said did not want to be identified. "They are in turn bored and excited, they want action, they are callous, they are enormously arrogant."

Experiences like that have fed the antidraft campaign that activists like Cherry are trying to organize. She says her group is seeing signs of "an enormous amount of dissatisfaction" among conscripts, including an increase in the number of soldiers who refuse orders to enter the townships, although she has no figures.

Religious objectors must do six years of alternative community service. All others who refuse to serve face six years' imprisonment.

So far, the Army has not taken a hard line against those who refuse to do township patrols, usually deferring their call-up or offering them alternative duty in an attempt to avoid confrontations that might further divide the country's shaken white minority.

"The Defense Force has a people-oriented approach, so it is inconceivable that an intractable attitude would be applied to such a sensitive issue," said Army spokesman Buck.

One known exception was Rifleman Alan Dodson, a young lawyer who was fined $250 in August after being court-martialed for refusing to go on patrol in a township.

The court acknowledged that Dodson, who had won a medal during his previous service, was "a fine, outstanding young man" but said some sort of penalty was necessary as an example to others. "We are standing with our backs to the wall and are fighting for our survival," the court said.

The antidraft campaign, founded two years ago, has had to tread carefully under the state Defense Act, which makes it a crime to "depress or alarm" the public in defense matters or to encourage or assist anyone in dodging the draft.

Officials have derided the campaign's claims of growing resistance. When the anticonscription group contended that an unprecedented 7,600 persons had failed to report for last January's call-up, the Army replied that most were students entitled to further deferments or persons who had changed addresses without notifying the military. Fewer than 200 were bona fide draft dodgers, the Army said.

Nonetheless, the security police appear to take the campaign seriously. Four of its leaders were detained for about two weeks last month, and 20 houses of campaign leaders were raided.

Adriaan Vlok, deputy minister of defense and law and order, accused the campaign of conspiring with the outlawed African National Congress "to break down the will of our young men and women to defend our country."