The general's helicopter banked hard over the clouded forest. Mist beaded on the windows and wet the face of the starboard gunner as the door was thrown open and his M60 machine gun blasted away at the trails beneath us, hammering 30-caliber bullets into fire-scarred Indian settlements and small plots covered with broken cornstalks.

"Dales! Dales! Dales!"--Give it to them!--the general shouted like a huntsman above the din of the engines and the crack of the bullets.

Two or three leftist rebels had attacked a small government patrol not far from the Pan American Highway, and Gen. Benedicto Lucas Garcia's helicopter, with two journalists aboard, had moved into action.

It was one of countless skirmishes in the guerrilla war raging through northwest Guatemala and rapidly spreading: a fight for control of the largest, richest, most populous nation in Central America.

On one side is a conservative, military-dominated regime that has become an international pariah for its dismal human rights record. On the other are leftist and Marxist guerrillas, many of whom have links with Havana and are working hard to win over this nation's Indian population.

The war already has taken on proportions comparable to the Salvadoran conflict.

The rugged countryside with its heavy foliage is perfect for insurgents. The government's intransigence on human rights issues--including its refusal to respond substantively to widespread charges that it is responsible for thousands of civilian deaths or to allow recognized international human rights agencies to visit the country--however, has cut it off from the kind of military assistance being funneled by the United States, its traditional supplier, to El Salvador's government. Meanwhile, the economy that was flourishing only three years ago is headed for the rocks as the violence erodes investor confidence.

The roots of the war are fixed in desperate economic, social, cultural, even racial disparities.

Through more than 20 years, the conflict has simmered, erupted, raged, been reduced then resurrected. Tens of thousands have died, many of them abducted, tortured; some disappeared or simply were shot down in the streets by "unknown men" or by "death squads" often linked to the government.

Yet never has the war been like this, with the government waging what amounts to scorched-earth campaigns in some areas and the guerrillas ever more aggressive. This week the latter used sabotage to black out the capital and mounted a full-scale attack on the heavily armed garrison in the town of San Juan Cotzal.

Until last summer the Guatemalan Army seemed fairly confident of its ability to deal with the guerrillas and remained in its cuarteles, or garrisons. But after raids on 30 safe houses of the guerrilla faction known as the Revolutionary Organization of People in Arms, military officials were stunned by the level of organization, armament and infrastructure they found.

In August, Lucas, the flamboyant brother of President Romeo Lucas Garcia, was appointed chief of staff of the armed forces. Trained at Saint-Cyr, France, during the Algerian war and a veteran of several field commands, Benedicto Lucas transformed the Army's tactics.

By November, the Army had begun a major drive through the province of Chimaltenango, just west of the capital. Again, it found a level of rebel entrenchment and sophistication that gave them pause.

In much of the area, Vietnamese-style man-traps of sharpened sticks had been laid; hillsides were riddled with tunnels; as many as 200 storerooms were found. What Lucas called "committed villages" were prepared with trenches.

Lucas claims that Chimaltenango is now "totally pacified."

The plan of battle was based on the chief of staff's analysis of the guerrilla organization, particularly of the faction known as the Guerrilla Army of the Poor, or EGP for its Spanish initials, which has its strongest units in the northwest.

"The EGP began to work in 1976, to indoctrinate the people and form what are called familial nuclei, where the husband acts as the combatant, the wife as collaborator in all that the term implies--supply, preparation of food and everything--and the children from 8 to about 15 are agents of theirs who harrass the Army with homemade grenades," said Lucas.

"Then there are irregular local forces that also aid the guerrillas and warn them of the Army's coming," he continued. "Of course, these people are difficult to distinguish from most of the rest of the local population, but these organizational bases have to be won over or wiped out.

"Because of that, well, the population suffers."

"We have to attack with sufficient numbers to surround the guerrillas," said Lucas. For that reason, he said, 5,000 troops were sent into Chimaltenango, and as many as 15,000 of his 22,000-man armed forces are now being deployed in El Quiche. During the Chimaltenango campaign, Lucas claims, 2,000 people he classifies as guerrillas were killed while he lost only a few of his own men.

While foreign officials generally consider these figures exaggerated, there is no doubt that the war is taking a heavy toll on the rural population.

As the helicopter whirred over the treetops, its gunners, one in uniform, another a major in civilian clothes, blasted at anything and everything beneath them.

A small dog scurried, frantic and alone, down a narrow, winding trail. As Guatemalan troops deployed beneath us, the rest of the forest seemed still.

Nobody else could be seen. Not guerrillas, not the peasants who once worked these fields. No one.

Elsewhere, the insurgents have begun to strike back in force.

While major roads in northwestern Guatemala, completely blocked by the guerrillas only a few weeks ago, have been cleared, local residents and soldiers say the fighting remains constant. According to troops in the garrison at Santa Cruz del Quiche, their patrols are ambushed at least once a week and, according to one young officer, "sometimes three or four times in a day."

This week, coincident with the 10th anniversary of the EGP's founding, guerrilla activity increased dramatically.

They not only stepped up ambushes and sabotage, bombing several buildings in the capital and wrecking a key power station, but they changed the focus of some attacks.

At 5:30 Tuesday morning, a large force of uniformed guerrillas attacked the military headquarters at San Juan Cotzal in the heart of El Quiche, the rough mountain province where the guerrillas are believed strongest.

The insurgents fought their way to the walls of the garrison using heavy-caliber machine guns, Chinese mortars and rocket-propelled grenades. According to witnesses and soldiers, the guerrillas came close to overrunning the headquarters.

At least a dozen soldiers died and nine more were reported wounded. Before, the guerrillas had never even tried such an assault. The casualties they suffered are unknown.

Arriving on the scene shortly afterward, the chief of staff said the guerrillas would change out of their uniforms into peasant clothes and bury their arms, but he deployed 1,500 men to track them down.

The secret war continues as well.

Terrorism has increased on both sides. Reported deaths that appear politically motivated surged from 100 a month in 1980 to more than 300 a month in 1981. Most recently it has been close to 500. Foreign officials concerned with human rights problems believe, moreover, that these figures are low.

Firefighters in the market town of Chichicastenango say they regularly find bodies by the road, murdered by "who knows who," but have no idea how many are simply buried by peasants. The hospital in Santa Cruz, now the only one in the area, reportedly estimates that 1,500 people died violently, and most of them mysteriously, in El Quiche in 1981.

The capital still bustles peacefully, but assassinations in broad daylight remain commonplace and many major buildings are roped off, with any car trying to park nearby searched for bombs.

There is little serious optimism here. Elections scheduled for March may provide a slight opening for a political solution, but it is possible that not even a cosmetic change will come about if, as expected, the official military candidate wins.

Meanwhile, the war worsens daily. The United States, reluctant to support a government with a reputation like Guatemala's but also concerned about a radical leftist takeover, has relegated itself, at least in terms of public policy, to the sidelines.