Sgt. "Jumbo" van der Merwe, veteran of wars in the Congo and Rhodesia, poked his head into the cockpit of the mine-proofed vehicle called a buffel . He warned the nine white soldiers, automatic rifles at the ready, to stay alert because there is "a lot of activity" on the road.

This buffel (an Afrikaans word for buffalo) headed the military convoy bringing supplies from Oshakait, the main South African military base in this operational area, to field headquarters to South African Infantry Battalion 54 -- a tent camp at Eenhana, six miles from the Namibian border with Angola.

The straight, sandy road stretched out ahead looking like a giant wooden match on its side. Midway, teh convoy met the mine-sweeping patrol that had set out from Oshakati five hours earlier, as it does every morning, to detect land mines laid by the Soviet-backed People's Liberation Army of Namibia (PLAN), the guerrilla wing of the Southwest Africa People's Organization (SWAPO).

Ten young, white soldiers, sweating and dusty, trudged along the road, their lives protected only by the mine detectors outstretched in their hands.

"This war is good for us," one of the soldiers in the buffel leaned over to say. "It's giving us a lot of experience."

These South Africans belong to a generation conditioned to believe that a communist-inspired "onslaught" against their country is inevitable. They were just toddlers at the outbreak of this conflict, one of the longest running on the continent.

In 1965 six blacks armed with Soviet submachine guns and pistols entered Namibia from Angola and set up a recruiting base at Ongulumbashe. This obscure, oblong-shaped country, ruled by South Africa as South West Africa since World War I, was guarded at that time by 650 police officers. Today at least 20,000 South African troops are here fighting about 6,000 black insurgents based in neighboring Angola.

For South Africa, whose presence here was declared invalid by the United Nations in 1966, the war is much more than a struggle for control of a vast piece of semi-desert as big as Texas and Oklahoma combined and covering some of the richest uranium and diamond reserves in the world.

Rather, it is increasingly apparent that here, 800 miles from its own borders and the public awareness of its own people, South Africa is desperately trying to reverse the trend of the past six years in southern Africa when guerrilla movements took power in Angola, Mozambique and Zimbabwe. The repercussions of a similar outcome here could rumble like thunder through the black community in "the States," as the soldiers refer to South Africa.

The South Africans declined in January to sign a Western-designed plan for a cease-fire and independence elections in Namibia. One of the reasons for that decision can easily be discovered on a visit to the "operational area." The morale of the South Africans is high. They say they are beating SWAPO, and as one colonel put it, "Winners don't sign cease-fires."

The commanding officer in Namibia, Maj. Gen. Charles Lloyd acknowledges that this war will eventually have to end with a political solution. But in the meantime, he said in an interview, his military objective is clear: "to eliminate SWAPO as a military force, break its will to fight" and to convince "people of common sense" of the "futility" of SWAPO's fight against the South Africans.

Although the South Africans appear to have the upper hand militarily at the moment, they are a long way from achieving Lloyd's objective. And SWAPO is even further away from being able to defeat the South Africans.

The heart of the war is in Ovamboland, an Arkansas-sized plain of mopane palms and thorn trees on the border with Angola. SWAPO has its greatest support and draws most of its recruits from the 450,000 Ovambos living here.

With almost half of Namibia's population, Ovamboland is the key to political control of the territory, one of the factors leading to the South African rejection of the Western ceasefire.

"To the military mind, it [the ceasefire] would not work because if the South African forces withdraw [as the plan called for] we would lose control over 80 percent of the population," said Commandant Adriaan Kleynhans.

"That's what this war is about, control of the masses, whoever has control of the masses, will win the war in the end."

"This is a man's world," read the poster in the corridor that leads to the officer of Brig. Gen. Rudolf Badenhorst, known to his troops as "Danger." Badenhorst, who runs the war in Ovamboland from the Oshankati base, says his forces are more in control than 18 months ago and that "the situation will still improve."

He paints a bleak picture of SWAPO's situation, claiming its morale is low and food and new recruits hard to get.

south Africa says it killed 1,447 "terrorists" in 1980. It admits to losing 95 men. So far this year, almost 400 SWAPO insurgents have been killed and 9 South Africans, according to South African figures.

One of the reasons South Africa has the upper hand militarily now is that it has taken its war into southern Angola.

"We had very strong political restraints on our military operations up to about 18 months ago," said Kleynhans."But then we became more aggressive, we got permission to attack SWAPO bases in Angola."

Since then, South Africa, undeterred either by protests of the West and the United Nations or by the presence of Soviet, East German and Cuban troops in Angola, has struck SWAPO facilities as far as 200 miles inside Angola. Its air and ground forces operate daily on Angolan terrain.

The South Africans also claim to be winning what they call the "real battle" -- for the hearts and minds of the "local population." Badenhorst estimates that 60 percent of the population, what he calls the "silent majority," is "positive" toward the South African forces and only 40 percent is "negative" or "neutral." Like most of his fellow officers he professes to believe that SWAPO would not win a "free and fair election."

If all this is not just military braggadocio for public consumption, then the South African defense force may well be wandering in a minefield of its own delusions.

Although the South Africans say they "dominate the terrain," the insurgents keep coming. A group of about 40 penetrated the white farming area of Tsumeb south of Ovamboland two weeks ago.

South African officers admit they find more mines on the roads now than they did a year ago. Telephone poles, water pipes and bridges are blown up regularly. On Jan. 31 guerrillas attacked the Oshakati base with 122mm rockets and a few days later blew up the bridge on the main road between the base and the airfield at Ondangwa.

Briefing his men for a security patrol around Eenhana camp, Lt. Christo Retief warned the "the 'local pops' don't usually give us information on the enemy." In a another briefing, Keynhans admitted that "the enemy moves in civilian clothes and operates at night [despite a dusk-to-dawn curfew] quite extensively. The facts are they are getting to the people."

None of the political parties opposed to SWAPO hold public meetings in Ovamboland, and the elections for a local government were canceled last year on security grounds.

Black critics of South Africa's war effort dismiss as "wishful thinking" claims that SWAPO is losing support.

As in all wars like this, it is the civilians who suffer most and they suffer from both sides. Overwhelmingly, they are the victims of land mines; in 1980, 126 died and 173 were injured from the blasts, according to South African figures.

A letter to the Windhoek Observer newspaper commented: "Today's stories from the north are incredible, they tell of villagers being rounded up and men and women of all ages made to lie on their stomachs in long queues for hours on end, innocent people being beaten up mercilessly and houses burnt down to ashes."

Meanwhile, South Africa is pushing ahead with the creation of a South West African Territorial Force that by 1984 will be larger than 13 other African armies and eventually comparable to those of Angola and Tanzania, according to Col. Ken Snowball. In January it introduced conscription for all Namibian males to fill this force. Ovambos were extempted since the South Africans said they had enough Ovambo volunteers.

Through these two moves, South Africa is implacably hardening the tribal antagonism between the Ovambos and other ethnic groups and it is shifting the burden of the war onto Namibians regardless of whether they want to fight SWAPO. Nonwhites account for 38 percent of the troops in the operational area.