SANTO TOMAS, Nicaragua — When 400 soldiers walked into this cattle town the other morning, many residents, just waking up, mistook them for a government battalion.
After all, the camouflage uniforms looked official, and the men wearing them acted as if they were in charge. In six years of war, Santo Tomas, home to 10,000 people and the Sandinista army's 52nd Brigade, had never been attacked by the Nicaraguan contras.
But the contras were here. Their sudden appearance, which set off three hours of street fighting, was part of the biggest anti-Sandinista offensive this year. It was aimed at forcing the government to negotiate with the rebel leadership under terms of a Central American peace accord.
Frightened townspeople, who hid under beds and in church as bullets and rockets whizzed outside, said the contras had made their point before retreating. Many said they agreed with the rebel position.
Defense Minister Humberto Ortega said the attacks in Santo Tomas and elsewhere along Nicaragua's only east-west highway Thursday were "a desperate act" by the United States, which finances and trains the rebels.
"The person with whom we have to arrange a cease-fire," Ortega said, "is the chief of the mercenaries, he who calls himself a contra, Ronald Reagan."
But interviews here and in other embattled towns since the peace accord was signed Aug. 7 indicate that most people, while reluctant to voice support for the contras, believe there can be no peace until the Nicaraguan parties in conflict agree to talk.
"There is something I do not understand about this government," said Candida Pacheco, a 44-year-old mother of six in Santo Tomas. "They say they signed a document to bring us peace, but they will not talk to those who are fighting in the mountains. If they truly want peace, that's what they ought to do."
By signing the five-nation accord, Nicaragua agreed to arrange a cease-fire and restore full political and press freedoms by Nov. 7, in exchange for a cutoff of outside aid to the rebels.
The agreement does not explicitly require cease-fire talks with the contras, but Nicaragua's Roman Catholic bishops and other Central American presidents have called for such talks. The Reagan Administration argues that the Sandinistas' refusal to negotiate would justify new military aid for the contras.
Though President Daniel Ortega is said to be reconsidering Managua's position, the Sandinistas publicly refuse to talk to the contras, calling them an artificial insurgency made in the U.S.A.
Instead, the government has declared unilateral cease-fires in four small war zones in an effort to get rebels to surrender to local peace councils and accept an amnesty. But few have done so.
'There Have to Be Negotiations'
"We cannot appeal to them to surrender unless there is real conciliation," said Antonio Vivas, a Protestant minister on the peace council in Nueva Guinea, near one of the truce zones. "There have to be negotiations. Ninety percent of the people here feel that way."
The peace council in Santo Tomas, which is not in a cease-fire zone, has refused to promote the amnesty offer. "Here the people want a cease-fire acceptable to both sides," said Father Peter d'Abele, one of the town's two Roman Catholic priests. "A cease-fire by only one side is worth nothing."
To prove that point, the contras have stepped up their attacks. Last week they shot down two Sandinista helicopters with portable heat-seeking missiles before attacking Santo Tomas and three other towns in a 60-mile stretch along the Rama Road.
The road, over which the Sandinistas move Soviet-supplied weapons from the Caribbean port of Bluefields to Managua, was closed two days by the fighting. The army said it successfully defended important military targets, while losing 44 soldiers and killing 61 of the 700 rebels who staged the raids.
However, the contras damaged an army fuel depot in Santo Tomas, destroyed two army trucks and blew out a small bridge just east of town before Sandinista reinforcements landed in four helicopters to drive them back to the hills.
"The psychological impact of the operation was more important," Bosco Matamoros, a contra spokesman, said in a telephone interview from Washington. "We showed that the Sandinistas do not have absolute power in an area of strategic importance to them."
The priests and other residents said the rebels killed at least 12 Sandinista soldiers in Santo Tomas while losing three of their own men but appeared to make an effort to avoid hurting civilians.
Once the fighting started, they said, the rebels ordered civilians to stay indoors. Father D'Abele said many people raced through the cross-fire into his church after many of the army's outnumbered soldiers and reservists intruded in their homes seeking cover.
Several houses had tin roofs torn off by rebel rocket fire, but no civilian deaths were reported. Red Cross workers said they treated 20 wounded civilians, mostly women and children.
The contras seized 12 men during the raid and marched them out of town in an effort to recruit them, according to Roger Barberena, one of several who escaped the next day. He said some of the captives were made to carry dead or wounded rebels.
"Nobody can hide what happened in Santo Tomas that day," said a 55-year-old woman who would not give her name. "For three hours the contras went wherever they wanted. This shows they have great support and are capable of taking over the town."