The top field commander in the Salvadorean Army, Lt. Col. Domingo Monterrosa, died late Tuesday afternoon in an apparent helicopter crash. The incident - which also took the lives of the commander of elite rapid-reaction Aclacatl Battalion and several other top military commanders - occurred during a major campaign by Colonel Monterrosa to move into rebel-held territory in northern Morazan Province.
The guerrillas claimed Tuesday that a rebel anti-aircraft unit downed the helicopter, but a spokesman for the Salvadorean military joint chiefs of staff told reporters that the helicopter had ''suffered an accident.''
''In no way will a situation like this affect the course of the war set by the joint chiefs of staff,'' said Lt. Col. Ricardo Cienfuegos, the military spokesman. ''These actions are normal in war.''
Colonel Monterrosa, who was widely regarded as the Army's most adept counterinsurgency strategist, told reporters last week that he hoped to capture leaders of the guerrilla movement in the Morazan campaign, which involves some 2 ,500 troops. He thought rebel leaders would be together in the area to make policy decisions in the wake of the last week's government-rebel talks.
''Sometimes you have to make war to achieve peace,'' Monterrosa said. ''My understanding is that we're in a war although we're trying to find peace. I haven't heard anyone mention a cease-fire. They (the guerrillas) haven't stopped and we haven't stopped.''
One of those Monterrosa hoped to capture was Joaquin Villalobos, the overall military commander for the rebels and the architect of the rebels' major military victories. In many ways, the war in eastern El Salvador was a battle between Monterrosa and Villalobos.
The Salvadorean government was able to pinpoint the location of Villalobos when the rebels requested a helicopter to carry the guerrilla commander to the government-guerrilla talks last week, a request the Duarte administration turned down.
United States Ambassador Thomas Pickering issued a statement after the deaths saying, ''We have confidence in the Salvadorean government to continue along the course charted by President Duarte.''
Monterrosa's abilities as a commander were acknowledged even by the rebels. Guerrilla leaders noted an improvement in the performance of the Third Brigade troops when Monterrosa took charge last December. The colonel, who often put himself in precarious front-line positions, is credited with boosting soldier morale.
Monterrosa also had a reputation for using brutal military tactics. Many analysts say troops under his command were involved in at least three massacres of civilians, including 482 residents in the town of El Mozote in December 1981.
Rebel radio Venceremos was the first to publicly air news of Monterrosa's death. Referring to the downing of the helicopter, Venceremos said, ''In this action our people have vindicated the blood of thousands of peasants massacred by Domingo Monterrosa in El Mozote, Los Torinos, Plaza Onda, and many other villages in the northern department of Morazan.''