This is an anthill," said Jorge Melendez, alias Jonas, commander of the Farabundo Marti Liberation Front's northeastern forces. The hill on which he sat overlooks an unnaturally silent, deep, small valley, buried among the green mountains of Morazan Province in northeastern El Salvador.

"This is an anthill," Melendez repeated, and from one of a hundred invisible footpaths the first water carrier appeared, perspiring from the effort of balancing a full jug on his head straight uphill for 15 minutes.

Over the last two years, guerrillas of the Farabundo Marti Liberation Front, fighting to overthrow the U.S.-supported Christian Democratic-military government, have increased their hold on portions of northern El Salvador. During a two-week visit to this northern zone, conversations and observations indicated that the guerrillas are following a two-pronged strategy in the expectation that they can force the government to negotiate with them.

First, they are attempting to consolidate their hold on more pockets of territory, like the one visited, with populations that are self-sufficient, stable and loyal. Second, the guerrillas are increasing the frequency and intensity of their military attacks in the weeks preceding elections the government has scheduled for March.

The guerrillas agreed to take reporters on guided trips through this area in an evident effort to gain international credibility and to strengthen their bargaining position in eventual peace negotiations. The rare access to one of what they call their "control zones" began with a three-day walk over steep hills and mountains to the improvised hilltop barracks where Jonas sat, wearing a U.S. Army camouflage jacket in spite of the heat.

The water carrier nodded briefly to Melendez and puffed on to the "barracks," a one-room adobe house where another man immediately started ladling some of the water over dirty plastic cups and gourds used as dishes. A third man cranked cornmeal for tortillas out of a meat grinder, and a woman bent over a stone mortar ground the meal into an even finer paste which a second woman then patted into large flat patties and placed on a grill to bake.

A young girl placed an empty plastic water jug on her head and started downhill to the spring. Several armed guerrillas took turns beating a sack of dried corn with a machete to free the kernels. It was a scene of uninterrupted laboriousness to be repeated at every camp visited.

Six thousand people are estimated to be living in this zone. The day-to-day existence of the acampamentados, the "camped-out ones," as they call themselves, blurs distinctions between civilian and military populations. The peasants talked to in the "control zone" described themselves as guerrillas, but they distinguish between those who do nothing but prepare for and participate in combat--the muchachos (boys) or combatientes (fighters)--and those who devote themselves to support work and production.

There also appear to be two kinds of camps: smaller ones, like the one where Melendez was interviewed, with perhaps 20 troops, strict military discipline and camouflaged anti-air raid defenses, and the larger, more relaxed farms.

A two-week stay in the "anthill" provided one glimpse of El Salvador's civil war as a home-grown insurrection, at least in this region. The government in San Salvador and the Reagan administration have repeatedly described El Salvador's civil war as a foreign-inspired and directed revolution that is essentially run by Cuba and other Soviet proxies. In Morazan Province, the war is being fought largely by radicalized local peasant guerrillas who maintain a "boarding school" for 80 children, a military "academy" for 20 students, several primitive sugar mills, a radio station that broadcasts throughout Central America two hours daily, an explosives workshop and many farms.

They have little in common with Nicaragua's citified Sandinistas but much that recalls the historical accounts of Mexico's bloody peasant uprising in the early part of this century.

Like the Mexican rebels, the Morazan peasants are intensely religious, largely illiterate and devoted to their own particular region. The family plays a vital role in their tradition, and large numbers of traditional women who will risk their lives to ensure an adequate supply of properly made tortillas for their men do not deem it appropriate to carry weapons.

Without exception, both men and women repeat the same motivation for joining the guerrillas: "To end the repression."

"People started living in camps two years ago," says Nolvo, formerly a well-off peasant now in charge of "militias and mass organizations" for the area. Like most people in the guerrilla-controlled regions, Nolvo uses a nom de guerre rather than his real name.

"The Army had a great repression here in August and October of 1980 and most people fled to refugee camps," he said. "Those of us who stayed behind couldn't live in our homes any more. We were hiding all the time from the government, sleeping in the hills or in our cornfields, and we started banding together for protection. Everything has been collectivized since then."

"Repression" has long been a part of the peasant lexicon in El Salvador, where decades of harsh military rule in support of a landowning oligarchy ostensibly ended after an October 1979 coup by progressive young Army officers. The new rulers offered to share power with civilian political groups, and promised political, social and economic reforms.

The reformist coup at least temporarily knocked the steam out of the small Marxist guerrilla bands that had long fought the military from the hills. But the repression, they and the peasants here maintain, soon began again and quickly intensified as the government fought its own internal battle between reformists and those promoting the status quo.

The government and the guerrillas agree that it has been the noncombatant peasantry that has suffered the most in the civil war, with death statistics over the past two years running into the tens of thousands. The guerrillas, and the peasants here, as well as international human rights organizations and opponents of U.S. support for the junta, maintain that the military and its allies are doing most of the killing in an effort to wipe out potential bases of guerrilla support.

While the junta and its backers in Washington acknowledge that there have been abuses by the military, they maintain that the guerrillas themselves are guilty of mass terror of the peasantry. Each side accuses the other of altering the body count, and distorting the blame, to discredit the other.

The narrow footpaths connecting the camps sometimes give the impression of a conveyor belt. Nolvo escorts a visitor to a tailor shop and along the way stops several times to receive messages from a courier. He sends on answers to questions about production and distribution of raw sugar, maize, plantains and livestock.

Finally, the dusty path turns off at a large, formerly prosperous farmhouse with whitewashed adobe walls and a brick floor. Six wrought-iron sewing machines sit in the shade of a spacious portico, and at them an equal number of tailors pedals away, cutting, snipping, shaping and biting the threads off caps, shirts and knapsacks sent in for repairs.

"We were all tailors before the war," says Lino, head of the shop. "Now the organization has decided this is where we are most useful."

Inside the cool dark room, men and women squat sorting grain. The dry cornstalks are husked, separated by size, packed in burlap sacks and sent on their way. In the kitchen are the ever-present tortilla ladies. As always, the dry, parsimonious peasants offer a small present: this time, an orange and a bit of raw sugar.

Many hours down the road the fatigued traveler encounters a trapiche, a 16th century-style sugar mill which employs two oxen to grind one stalk of cane at a time. The cane juice is boiled down into a thick black syrup which then congeals into cakes in what looks like a gigantic muffin pan carved out of an entire log.

"We produce as much as 300 pounds of sugar a day for our fighters," the guerrilla guide says. "They can last in the trenches for as long as four days with nothing but raw sugar and water. This is very sweet work that we do," he jokes, and his fellow workers cackle in appreciation.

Yet another invisible path through the bushes surrounding the sugar mill leads to a tiny adobe house, in front of which six clay grills stand drying. Dona Ignacia, the potter, appears in the doorway. Dressed Indian-style in an immaculate white dress and red glass bead necklaces, she beams at her work in progress, a large perfect sphere of a jug she is hollowing out of the clay brought from a mountain on muleback. She has never heard of the potter's wheel.

"I had taken refuge outside the country when I heard that the muchachos needed plates," she says. "So I came back. Take a picture of me with this pot. It's very nice."

Like every peasant interviewed, Dona Ignacia said she had lost members of her family in the past two years' fighting. Like all the others, she answered "to end the repression," when asked why she had joined the guerrillas. Like Reyno, the paramedic; Leandro, the farmer; Alvaro, the military instructor and all the peasants interviewed in Morazan, Dona Ignacia reflects her pragmatic radicalism in her vocabulary.

Terms like "exploitation," "oligarchy" and "Yankee imperialism" fall easily from everyone's lips, but there is a great distance between their political thinking and the articulate university-bred leftist views of the fewer than a dozen people encountered who, like Melendez, were not born and raised in Morazan.

These included Adonis, a 17-year-old radio technician from San Salvador; the Rev. Rogelio Ponseele, a 42-year-old Louvain-educated Belgian priest; Blandino Nerio, 24, freed from prison seven months ago and now in charge of the guerrillas' radio programming; and Lucas, a 39-year-old North American who has been with the guerrillas for more than a year.

There were also two Mexican volunteer doctors and one from San Salvador, and the "press and propaganda" team from San Salvador: Leoncio Pichinte, a tiny, nervous organizer with a seventh-grade education who is now a member of the northeastern front's high command, and "Butterfly," a slim and hyperkinetic young woman with a guitar whose voice is frequently heard on the guerrilla radio's broadcasts.

These city people are more representative of the leadership of the Farabundo Marti guerrillas, who are not fighting simply "to end the repression."

"Our program includes the formation of a government of ample participation and a new-style army, incorporating the healthy elements of the government forces and our own guerrilla columns," says Melendez. "We want to negotiate a settlement, but realistically, we know the regime will never talk to us unless it is forced to do so by our position of military strength."