At the time when this exploration by land of the region between the Atlantic Ocean and the river _Paraguay_ was being so successfully carried out under the leadership of Cabeza de Vaca, another expedition, of still greater geographical importance, was being effected elsewhere on the same Continent; but before describing the discovery of the _Amazons_, it is necessary to go back to the circumstances of which it was one of the results. In reconnoitering the course of exploration over a vast continent, it is impossible to relate the events of each year in the exact order in which they occurred. One must take the discovery of one region after another, going back when necessary to recount other explorations elsewhere which may have meanwhile occurred simultaneously with those already described. It may therefore be desirable here to follow the proceedings of Cabeza de Vaca in _Paraguay_. His first care was to send down vessels to _Buenos Ayres_ to the relief of that portion of his force which had been despatched by sea from _Santa Catalina_ to the latter place. It was obviously of the first advantage to the public interest that the settlement of _Buenos Ayres_ should be re-established. Without some port near the sea the settlers in the interior would ever be at a loss for the means of communication with Spain. The vessels from _Santa Catalina_ had reached _Buenos Ayres_ long before the arrival of those sent from _Asuncion_, and during the interval the Spaniards brought by the former had nearly perished from hunger. The force from _Paraguay_ arrived in time to enable them to resist a formidable attack from the natives. They attempted to fulfil the governor’s orders to rebuild the town; but they were at length discouraged by the incessant rain, and abandoning the attempt, embarked for _Asuncion_.