The band of rebels armed with Soviet- and Chinese-made automatic rifles was preparing for a raid into Nicaragua at this camp 30 minutes from the Costa Rica-Nicaragua border.
Most of them were young Nicaraguan peasants who said they wanted to fight communism. Some were Costa Ricans. Most of them had joined the anti-Sandinistas only over the previous few months.
But the group of 50 fighters was just one small part of the larger guerrilla force of more than 2,000 which their leader, Eden Pastora Gomez, claims to have mustered in this southern zone. And today these forces of the Democratic Revolutionary Alliance (ARDE) are in what Pastora announced last week as ''strategic retreat.''
Pastora - the famed Commander Zero of Nicaragua's revolution - says he could field 15,000 more men if he had the guns. But both guns and money are lacking. ARDE's civilian leader, Alfonso Robelo Callejas, reportedly failed in his Washington quest last week for $200,000 to $300,000 a month for the southern ARDE drive to overthrow the Nicaraguan government.
Many analysts say Pastora's current ''retreat'' may be a ploy to pressure the Reagan administration to give him more money. The administration already provides funds to one anti-Sandinista group, the Nicaraguan Democratic Force based in Honduras, on the pretext that the group is trying to stop the flow of arms to guerrillas in El Salvador.
Pastora's group in the southern zone would have difficulty claiming to have any such function.
ARDE members say the United States has tried to pressure them to unite with the Honduran-based counterrevolutionaries. But Pastora has refused, not wishing to be too closely associated with those former National Guard elements now mixed in among the Honduran-based guerrilla forces.
It was only this year that Pastora announced he had troops fighting near the Costa Rican border. Although he says he has at least 2,000 men, Pastora probably has only about 750 soldiers, say sources here. Most of his men are from this southern border area, and the Rio San Juan Province where ARDE operates has only about 35,000 inhabitants.
The Costa Rican government has repeatedly denied that ARDE has bases in Costa Rica, but in Los Chiles it is an open secret that it does.
Currently, ARDE obstructs water traffic along the San Juan River, which forms the Nicaragua-Costa Rica border. The Sandinistas cannot hope to successfully contest control of the river since ARDE's posts are on the Costa Rican side, according to a journalist who visited the area in May. ARDE reportedly also has guerrilla bands near San Carlos in Nicaragua, north of Los Chiles. More than 20 clashes have been reported since May 1, when, according to the Nicaraguan government, 10 peasants, all Sandinista supporters, were kidnapped and killed by ARDE forces.
The San Juan River area is one of the most underdeveloped and isolated parts of Nicaragua and the Sandinista 1979 revolution raised expectations but has brought little progress there. ARDE has recruited peasants in this area with religious, populist, and anticommunist rhetoric.
It was a blow to ARDE when the government on May 11 expelled a Spanish priest , the Rev. Timeteo Merino, who had been organizing pro-ARDE groups in the region. Two deserters from ARDE said in Los Chiles that they had been part of those groups.
Capt. Bosco Ceteno, head of the Nicaraguan Army in San Carlos, told reporters recently that he believes ARDE is counting on the United States to topple the Sandinistas, allowing ARDE to present itself as an alternative to the Sandinistas and the northern counterrevolutionary groups with ties to the old Somoza dictatorship.
But the US appears to be hesitant to give strong support to Pastora.
Foreign pressure on ARDE and the lack of funds has already split the ARDE coalition. The Nicaraguan Democratic Union-Revolutionary Armed Forces has abandoned ARDE and is said to be moving its several hundred members to Honduras.
But disunity is a characteristic of the Costa Rican-based counterrevolutionaries. Brooklyn Rivera, a leader of the Miskito Indian wing of ARDE, had some of his harshest words for fellow Miskito leader Steadman Fagoth Muller, whom he said has sold out to ''dark forces'' including the Honduran Army , the United States, and Argentina.
There are divisions within ARDE itself over Miskito demands for autonomous government for their eastern sector of Nicaragua. But a representative of Robelo's faction of ARDE says, ''We will guarantee the Miskitos municipal autonomy, like all other municipalities'' - not exactly what the Miskitos have in mind.
Although factions of ARDE are divided, Pastora has something going for him that few others have. He is a war hero who is still fondly remembered by Nicaraguans. And he has no connections with the despised former dictatorship. He is said to believe he could lose this edge if he worked with the former Somoza Guardsmen fighting in the north.