MY MOUNTAINEERING partner and I wanted no part of the threatening war. Argentina and Chile were rattling sabers at each other in a border dispute over three small islands with large off-shore oil reserves near the southern tip of South America.

Lanky, phlegmatic Bruce Fessenden and I were here for one reason: to climb and (we hoped) ski Aconcagua, the highest mountain in South America and, at 22,874 feet, the highest mountain in the Western Hemisphere.

Our sponsors at AeroPeru were excited; this year's snowfall had been the largest in Andean history. If all went well, we would ski more than 10,000 vertical feet of perfect, springtime corn snow. All did not go well.

The first time we tried to cross from Chile into Argentina, where Aconcagua stands, both nations closed their borders and sent their armies ranging through the Andean highlands on mameuvers. Bruce and I were turned back by armed guards at a roadblock. They wanted no lighthearted alpinists wandering through a war zone.

We lugged our alpine gear to the central bus terminal of Santiage, the elegant, bustling capital of Chile. We tried to book passage for Punta del Inca, Argentina, the staging ground for climbing Aconcagua. The terminal was in turmoil. Of the six bus lines that went to Argentina, half believed the borders would not reopen, while the other half were selling tickets but promising nothing.

We had arrived at 7 a.m. to get an early bus. By 10 most of the hopeful Chilean passengersd had given up and gone home, but Bruce and I were determined to stick it out. Amazingly, at 3 p.m. after eight hours of waiting, we were boarded and rolling toward the border, 150 miles away. The driver was still uncertain if we could actually enter Argentina, but "Ni Modo! It's a nice day for a bus ride."

The omens were auspicious. Half the passengers were children, all singing along with the bus music system as it blared old Elvis Presley tunes and themes from "Grease." We rocked and rolled through hours of desert, lush farmland and river canyons. And, to our relief, the guards at the gates were gone. The road was clear.

With great excitement we switchbacked up the mountain pass, cleared the Chilean customs in 15 minutes, splashed through the semiflooded, transandean tunnel and emerged in Argentina.

Slovenly Argentine troops lounged aroung the border station. One soldier walked by with his pants down. All were dirty, and all carried their automatic weapons with the studied sneers of old Clint Eastwood movies. A poster in the border control office depicted a blue-eyes, Germanic-looking Argentine soldier with a dueling scar, staring mercilessly at the enemies of his homeland. The slogan read, "LIBERTAD POR TODA LA VIDA" -- "Freedom for All Life" -- whatever that meant.

More soldiers with automatic weapons patrolled the military camp at Punta del Inca, the village at the foot of Aconcagua, 10 miles past the border. Feigning unconcern, Bruce and I walked by them and into the guard house.

Only a week ago the Argentine consul in Santiago had told me that prior to climbing Aconcagua we should register at this military camp. "Just sign in and go climbing," he had assured me with a grand smile.

But a porky sergeant told us otherwise. "Oh no, you have to go to Mendoza (a five-hour bus ride away) and get permission from the police." He refused to hear our arguments and showed us the door.

We met a furious German climber who had been waiting for two days at Punta del Inca for his permission papers, already approved and stamped in Mendoza, to be accopted here. He filled us in on the protocol: first we must go to Mendoza for a complete medical checkup ( $40 to $50), then to the Mendoza police station to be fingerprinted and photographed. Finally, gerprinted and photographed.Finally, we must visit the local Argentine Alpine Club and pay Sr. Parra to help us get all the papers approved.

I telephoned Parra to see if all this were really necessary. "Oh yes," he said. "You cannot go climbing without papers. Please come to Mendoza. I will be happy to help you." When I asked how long it would take between application and receipt of permission, Parra was evasive at first, then he relucatantly divulged the infornation that might cost him clients. He told me that the commanding general of the Aconcagua region had forbidden any more climbers to attempt the mountain until the border dispute was ended.

Bruce and I were perplexed. Should we try to sneak past the guards at midnight? Try a bribe? It was infuriating to be so close to the mountain and not be allowed to climb.

We called Parra the next morning to see if anything had changed -- nope. Then Bruce suggested we ask the sergeant one more time. It seemed hopeless, but I agreed to try. Again we strolled to the gruardhouse and pushed past the slouching soldiers with their bristling weapons. I asked the sergeant on duty, a different fellow than the night before, if the road to Chile would stil be open when we wanted to return.

"Si, claro !" he said with a pride and finality implying that mightly Argentina controlled the roads and would never let them close. I asked if the trail to Aconcagua would also always stay open.

"Si, claro !" he replied. Pointing to a map of the region tacked to the wall, he shot his jaw forward. "That is an Argentinian mountain, and we control it completely. Nobody can scare us into closing the trails."

"Then my friend and I can go up on the mountain?" I asked with forced nonchalance.

"Si, claro ! Sign this and you can go." He handed me a list of 16 names of a South African climbing team currently on the mountain, the last party allowed to pass. In utter disbelief we signed in, mumbled some thanks and ambled out the door as if we couldn't care less.

Once out of sight, we grabbed our equipment and raced for the mountain. Afraid that the guards might change their minds and come after us, we strode at a furious, double-time pace. With 65-pound packs we devoured the trail, crossed rivers and streams and glacial ice, refusing to stop until nightfall, Christmas Eve. In gratitude we hallooed old Christmas carols into the starlit sky.

We caught up with the South Africans at Base Camp 1 the next afternoon. Their expedition had hit trouble. One of their team, Robert Gray, a lieutenant in the Rhodesian Army, had been stricken with pneumonia and began vomiting flecks of blood. Then, other team members discovered a lone Mexican climber, Fernando Osorno, who had collapsed at a higher camp with high altitude pulmonary edema. His lungs were filling up with blood, while his resting pulse rate flashed between 120 and 130 beats a minute.

The leader of the South Africans shouldered the responsibility and hiked the 25 miles back to Punta del Inca to summon a rescure helicopter. Two days later the helicopter arrived, a disgraceful delay in the annals of mountain rescue. Fortunately, the climbers had received competent care before evacuation, and both survived.

Bruce and I moved on to Base Camp 2, a rough wooden hut beside an alpine pond. Tacked to the hut wall I found a tattered note from an Austrian team dated 11/11/78, barely six weeks before our arrival. It read: "Our two friends are trapped in te strom. Karl and I barely made it to this hut. We are desperate. We have fashioned skis from the walls of this hut. Though th snow comes as high as our chests at times, we will try to ski out to Punta del Inca to get heop."

The two skiing Austrians were successful. Their two friends on the mountain barely survived the rescue, and one died after lying in a coma for weeks in the Mendoza hospital.

Aconcagua is dangerous mountain. Though its regular climbing route offers few technical difficulties, severse onslaughts of weather have resulted in an injury rate (frostbite, pulmonary edena, broken limbs, and death) of 20 percent of all climbers attempting the summit. Those Austrians were hit by the worst recorded Andean snowfall.

That snowfall was the reason we had brought our skis. But now, six weeks later, after all our border delays, there were only a few scraps of snow on the entire mountain.

From Base Camp 2 Bruce and I moved up quickly to High Camp 1 at 17,921 feet. This camp, appropriately named Antarctica, was situated smack in the middle of a wide-open, windswept avalanche slope. The only reason to camp there was the presence of a small emergency hut, lashed to the mountain with steel cables. Unfortunately, high winds had ripped off the roof and door, and a small snowbank filled the interior. After three nights there for altitude acclimation, we felt ready to try for the summit.

It was New Year's Day. We rose at 6 a.m. and dressed quickly in layers of wool, fibrepile and nylon. Bruce fired up the stove and concocted a guley mush of oatmeal, nutritional yeast and protein powder.

The final shelter at 20,500 feet also was named Peron and had holes in the roof, but at least it afforded protection from the screaming winds. I felt strong, but Bruce was not at his best. We were trying to cram three days of climbing into one, and the pressure was on.

At a steady 60 miles-per-hour, the wind showed no sign of slackening, so we pushed on. With multiple layers of windproof "vapor barrier" nylon between my skin and the wind, I didn't feel uncomfortable. The wind was simply a force of resistance to be fought off and pushed through, relentlessly.

Bruce's overgloves were fitting poorly, cutting off circulation; his fingers were slowly succumbing to frostbite. He stopped repeatedly to rpotect his hands while I pushed ahead, 200, then 400 yards through the deafening gale. I turned and encouraged him to follow, but he hung back. I waved at him to come, but he remained. "Good-bye," I gestured and turned toward the mountain.

Most victims of accidents on Aconcagua are solo climbers, I remembered. After another two hours of steady clinbing, I reached a high ridge and stepped up to look over... and gasped. Aconcagua is a knife.

Emormously broad when seen from below, it is incredibly thin from northeast to southwest. I was standing on the ridge to th summit. The deadly steep south face dropped straight away thousands of feet to the valley below. I fought afainst gusting winds that urged me toward the edge, then retreated back to the north facing boulder fields.

A half-hour traverse and a final sprint through a band of red rocks, and I stepped onto the summit. 2:18 p.m.

The highest mountain in the Western Hemisphere towers above its sister peaks. Like an island in a white-capped sea, wind-raked Aconcagua stnads alone. To the north the monstrous Gussfeldt glacier sweeps toward the peaks of the bowed Penitentes.To the east no snow or vegetation break the blood-red and rust-red river canyons of the east fork of the Rio Horcones.The river itself rushes silty, red-brown through desolate canyons of cinder and stone. To the west lie the two peaks: La Cuerna, snow-robed and rock-crowned, and brown Catedral with its gullies thin-fluted with white. To the south lies the main fork of Rio Horcones, twisting 20 miles toward the highway home.

The summit's silvery cross had fallen over.A bright colored decal, stuck upon its shaft, proclaimed the Argentine soccer triumph -- "Mundial '78" -- an omnipresent theme.

For me 10 seconds of self-congratulations for another day's survival was enough. I yielded at last to the brutal winds and slipped over the edge of the ridge, back into the boulder gullies. Then I picked my way down toward camp. For me it had been a happy New Year's day.

Afterword: Bruce and five South Africans reached the summit on Jan. 5 and returned without unjuries.