For three generations, the ruling Somoza family sent its agents to the province of Chinandega -- to rural towns such as San Pedro, only 500 yards from the Honduran border -- to recruit peasant boys for service in Nicaragua's National Guard.

For those lucky enough to be selected, the life of a soldier under the Somozas meant decent wages and an education. It also meant an opportunity to escape the impoverished, dreary, near-feudal existence of Nicaragua's northern provinces for the relatively glamorous and sophisticated life of cities such as Managua, Leon and Esteli.

What the Somozas demanded in return was absolute loyalty and a willingness to fight when necessary. It was an equitable and understandable exchange, especially for youths who had nothing -- and could otherwise expect nothing -- in their lives.

"The Somozas gave these simple people candy and bullets, and they gave themselves in return," said Commander Roy, a young Sandinista guerrilla now in charge of defending Santo Tomas, a little hamlet on the Honduran border near San Pedro.

"They are ignorant," he said, "They have never known another system. They were born, they were influenced by the Somozas and they died. Nothing more."

For 46 years, the Somozas' bond with the National Guard extended beyond the sons of Chinandega to their parents, their wives and their children. Unlike other regions of Nicaragua, where the Sandinistas seem to be immensely popular, the bond with the Somozas has not been broken entirely here.

If Nicaragua's new government -- the government of the Sandinista National Liberation Front that only last month defeated then president Anastasio Somoza and his National Guard -- has an Achilles' heel, it is here in the strategically important Chinandega Province.

Whether the new government's weakness in this region will prove important remains to be seen. But the Sandinista leaders, both at the national level in Managua and at the local level here, are aware of the political and military problems they currently face in Chinandega, probably the only part of Nicaragua that remains at least partially loyal to Somoza.

"This is one of the most dangerous parts of the country because this is where the counterrevolution will start," Commander Emilio, who is in charge of the San Pedro garrison, said last Sunday. "It won't start in the center of the country. It will start at the frontier."

There are at least 2,000 National Guard troops living in camps or holed up in commandeered farmhouses on the Honduran side of the Guasaule River, which marks the border between Nicaragua and Honduras at the northern edge of the province of Chinandega.

According to Commander Emilio, whose real name is Propspero Elroy Lopez Martinez, about 60 armed members of the Guard are in Las Canas, Honduras, less than seven miles from San Pedro, and eight more are in others reportedly are in camps in cities such as El Triunio, Honduras, a few miles further away from the border.

Despite reports that these troops are dispirited and embittered against the Somozas and have been disarmed by the Honduran authorities, Jose Daniel Garcia Estrada, overall Sandinista commander for the northern sector of the province of Chinandega, with headquarters in Somotillo, said recently that he believes the Guard will reorganize.

They may try an invasion across the Guasaule or adopt guerrilla strategy to create a "psychology of terror" aimed, in the long run, at toppling Nicaragua's new revolutionary government in Managua, Garcia Estrada said.

Already, Garcia said, small but well-armed bands of National Guard soldiers have slipped across the border in Chinandega at night to harass Sandinista outposts and frighten the peasants who live in the mountainous border region.

What makes the situation particularly dangerous for the Sandinistas is that the guerrillas cannot be absolutely sure to whom the small farmers who live in towns along the border will give their loyalty, according to Garcia Estrada.

In addition to Chinandega's history as a prime recruting area for the National Guard, Commander Emilio said that, unlike more accessible parts of Nicaragua, the Sandinistas were not able to get to mountain towns along the border to explain their cause before the war ended.

When he arrived in San Pedro almost a month ago, Emilio said the townspeople "were afraid because the old regime said we were communists. You could say that 99.9 percent of them were pro-Somoza because we weren't able to reach remote areas like this. The repression was terrible."

But now that they know us better," he continued, "there's more communication. There's more trust. We have told them that they can return to their normal lives, speak freely and keep their political ideas."

Commander Emilio said that, in addition to the 16 Sandinista regulars he has in San Pedro, he can count on another 60 men from the village should an attack come. Meanwhile, trenches and other fortifications are being prepared to defend San Pedro, a lovely mountain village with old stone houses around a grassy field, which serves as the main square.

The 400 to 500 people who live in San Pedro are mostly small farmers who grow corn and raise cattle and chickens. Many of them own their own small plots of soil or pasture land.

A drive along the border, from Somotillo to San Pedro, a distance of about 35 miles, showed no signs that the Sandinistas have moved large numbers of troops into the area to defend it in case of attack. Indeed, except for the nighttime shooting that the Sandinistas say occurs with some regularity in different spots along the border, there is no sign of the National Guard, either.

But the Sandinista commanders interviewed Sunday said they are prepared to defend the area if an attack should occur. They say they will adopt the guerrilla strategy that served them so well during the war -- rather than take defensive positions in the towns, as might be expected now that they are in control.

Our only chance is to keep armed and ready," Commander Emilio explained. "There may be more of them on the other side, but we have sufficient strength. Our physical and moral condition makes us equal to 10 of the Guard."