Abstract

The San Juan River, along with the Lake of Nicaragua, form an almost complete natural interoceanic canal, so that it has always been in the sights of great world powers, due to its geostrategic importance. Therefore, it was a key element in the expansionist pretensions of the filibuster leader William Walker who, with the support of the slaveholders of southern United States, attempted to conquer the five Central American republics and annex them to that country. Even though Walker had kept such an important aquatic route under his control since 1856, he was not confronted there during the first stage of the National Campaign of 1856-1857, as it was known that he would invade Costa Rica through Guanacaste. However, for the second stage of the Campaign, the Costa Rican army conducted its greatest efforts in the San Juan River, to dispute the military strongholds of La Trinidad, Castillo Viejo and the fort of San Carlos. To accomplish this, it was necessary to enter the San Juan River through its two largest tributaries, the San Carlos and the Sarapiquí Rivers. This represented great and dangerous challenges, since Costa Rica’s soldiers had no experience in aquatic combats, nor in such an unknown region. In order to understand what happened then, this article presents an analysis -based upon various documentary sources and visits to both rivers- of the political, geographical and human factors that led to these rivers being key to the northern region of Costa Rica to become a determining scenario in the defense of freedom and sovereignty of the Central American countries.

Keyword: Filibusterism; San Carlos River; Sarapiquí River; William Walker; Máximo Blanco; José Joaquín Mora