The shifting battle front. The civil war in this tiny country has cost 65,000 lives. The Marxist guerrillas have stalemated US-backed armed forces eight times their size. With military victory unlikely, the Army has tried a new tactic: winning hearts and minds.

RENE EMILIO PONCE, the most powerful field commander in the Salvadoran military, leaps off the deck of the Army helicopter just as it touches ground near this isolated farming village. The tough-minded colonel and his troops stride past the clusters of barefoot women and children, past peasant farmers with callused hands and white sombreros.

Oddly, after eight years in the cross fire of the country's bitter civil war, many villagers are laughing and smiling. For, unlike past Army operations, Colonel Ponce is not here to flush out leftist guerrillas and their sympathizers. He is spearheading a recent Army effort to win the people over with food, medicine, and promises of future development projects.

Though fighting between the Army and the tenacious rebels of the Farabundo Mart'i National Liberation Front (FMLN) is intensifying, this is the core of Central America's hottest war: the battle for hearts and minds.

``These people have changed their conduct and attitude with respect to the armed forces,'' boasts Ponce, who may soon become the most influential man in El Salvador with his likely promotion to Army chief of staff. ``It hurts the guerrillas much more if we're taking away their base of support than if we're killing their combatants.''

But despite Ponce's optimism, he and other top commanders admit that the Army has made only modest advances. In the struggle for civilian sympathies, as in the rest of the bloody war that has claimed 65,000 lives, neither side has the upper hand.

Boosted by more than $800 million in direct United States military assistance since 1980, the Salvadoran Army has pre-vented the estimated 6,000 to 8,000 Marxist rebels from winning the war. And it has transformed itself from an inefficient, brutal bunch of 12,000 men into a professional counterrevolutionary force of 57,000 soldiers.

But despite the massive US support, the armed forces have not been able to defeat the rebels or win the hearts of the people.

Why not? A wide range of US and Salvadoran government officials, military officers, and political analysts offer several explanations:

The leftist rebels remain the most potent and elusive military insurgency in Latin America, even though their prospects for outright victory are slimmer than four years ago. While the FMLN receives political and strategic help from Nicaragua and Cuba, it is considered largely a home-grown creation, born of the repression and economic inequities of decades.

The war has not been a high priority for the US. Despite its financial commitment, it has sent mediocre military advisers who often give training inappropriate for a guerrilla war.

The Army's current hearts-and-minds campaign is designed more to manipulate people's behavior than to fundamentally change the miserable social conditions that perpetuate the war. With its emphasis on pep talks and charity, the civic-action strategy has so far failed to root out either poverty or mistrust.

The Army's fight for civilian sympathies is also hindered by its longtime reputation for brutality. For 50 years, the Army ruled with an iron fist in the interests of the country's elite. In the early '80s, it was linked to thousands of death-squad killings and other abuses.

The military's own structure makes it difficult to eliminate the abuses, as well as corruption and inefficiency. After completing the military academy, members of each tanda, or graduating class, rise through the ranks more on the basis of class affiliation than merit. Because of their alliances, officers feel they won't be held accountable for their actions, no matter how egregious they may be.

``The tanda system is one reason the Salvadoran Army can't win,'' says a Salvadoran military analyst. With the bounty of US aid, he says, good looters are rewarded more than good fighters. ``It condones corruption. You go into the Army not to be a hero, but to get rich.''

The tightly knit system creates a shield of immunity. Col. Mauricio Staben, for example, has been implicated by US and Salvadoran sources in an attempted coup, a kidnapping ring, and other cases of human rights violations. But neither the colonel nor any other officer has been convicted of human rights abuses. Colonel Staben is now Ponce's second in command at the 3rd Brigade in San Miguel.

Despite efforts to promote a merit-based system, the US has so far had little success in transforming the tanda system - or forcing the prosecution of any Army officer for past abuses.

But, prodded by the US, the Army has attempted to scrub its image, and it has come a long way from being public enemy No. 1. A Salvadoran academic says: ``Through the past eight years, the Army has gained a level of legitimacy it never had before.''

The large-scale massacres and civilian bombings of the early 1980s have largely subsided. Death-squad killings, while in a resurgence the past year, have dropped dramatically. And many powerful Army commanders like Ponce have become enthusiastic advocates for ``civic action'' campaigns.

But some peasants are not convinced the Army has changed. At a recent civic-action day in Cant'on El Brazo, in Usulut'an Province, an Army officer danced with a peasant woman as other rural farmers were handed free medicine. One group of bystanders said they didn't think the Army's goodwill was more than a one-time affair.

Other Army tactics - including so-called ``dirty tricks'' to ferret out guerrilla sympathizers - have tended to create more fear than sympathy. And according to human rights monitors, Army abuses have slowly risen this year.

The most striking example was the September massacre of 10 unarmed peasants in the hamlet of San Francisco. An Army battalion marched into town, rounded up 40 residents, and read off a list of names.

Rosa Emilia Rivas was one of those called - and the only one not killed. ``They blindfolded me, tied my hands behind my back, and said I had collaborated with subversives,'' she said the next day. The soldiers decided they had made a mistake and let her go. But the 10 other suspected rebel sympathizers - seven men, three women - were forced to walk down a steep ravine. Villagers said they heard two loud grenade blasts and several rounds of rifle fire.

The Army, which has appointed a special commission to investigate, officially states that the peasants died in a frantic guerrilla ambush. But a separate investigation showed that seven were shot in the back of the head at extremely close range.

Such an incident recalls the dark days of the early 1980s, casting a shadow over the Army's civic-action campaign.

Citing evidence that the Army high command is rattled by this case, some foreign diplomats and Salvadoran analysts suggest that the killings may reveal a fundamental split in the military. The fault line, they say, runs between senior officers who have fully embraced the US counterinsurgency strategy and younger officers tired of bowing to American demands and who favor a more aggressive military strategy.

In a secret document before the San Francisco killings, a group of senior officers indirectly accused the right-wing Nationalist Republican Alliance (ARENA) of meddling with the younger officers ``with the sole purpose of creating an internal crisis in our armed forces.''

The disgruntled senior officers also criticized the all-too-rapid rise of one particular military graduating class - that of 1966. Known as the tandona, or the ``big class,'' this conservative group of colonels was promoted en masse to top command positions in July.

Several of the class - including its cunning leader, Colonel Ponce - were in security units accused of harboring death squads in the early 1980s. Today, those same officers speak fervently of their commitment to the concepts of democracy and human rights.

But even as they mouth the words of US strategy, members of Ponce's powerful wing of the tandona express dissatisfaction with two things: the civilian government's inability to meet people's needs; and the ``slow-motion Vietnam'' produced by the US strategy of low-intensity conflict.

``We have to seek our own conception of the war,'' Col. Juan Orlando Zepeda says. ``The war may be low-intensity for the United States.... But for us, this is total conflict.''

Some US officials worry that the aggressive tandona colonels will be less willing to listen to US direction. It could reach a point, they say, where the US is paying for the war, but not controlling it.