This led to explorations being set on foot by the public authorities, in the years 1803, 1804, and 1805, the result of which was, the discovery of several new passes over the Cordillera, south of Mendoza, one of which, the pass de las Damas, was examined by the same M. de Souillac, already spoken of, who reported that at a very small expense it might be made practicable for the passage of wheel-carriages. It only remained to be shown whether or not it was possible to travel in a direct line across the pampas from any of those passes to Buenos Ayres.
In this state of things, Don Luis de la Cruz, an enterprising officer who had seen much of the Indians, offered to start from Antuco, in the province of Conception, the most southern of the passes yet known, to endeavour to reach Buenos Ayres by a straight course across the pampas. This proposal was accepted by the Governor of Chile, and in order to secure as far as possible the co-operation of the native tribes, which indeed was absolutely necessary to the success of the undertaking, the Caciques of the Pehuenches, who inhabited the country on the eastern slopes of the Cordillera, were summoned to hold a grand parlamento, or parley, to consider it. There had been long a friendly intercourse between them and the Spaniards, who, moreover, had at times afforded them protection from the attacks of their enemies; they therefore did not hesitate on this occasion to intimate to them that they expected in return all the good offices and aid which they could give to Cruz and his party.
They attended at the time appointed, and after a grave discussion after their fashion, which lasted several days, they agreed to take the expedition under their particular protection, and see it safe to Buenos Ayres; Cruz, on his part, engaging that the Indians who accompanied him should be presented to the Viceroy, rewarded with suitable presents, and sent back in safety to their friends at the conclusion of the service. This pact was ratified with much formality; the hand of Cruz being solemnly placed in that of the most ancient of the Caciques, to signify that thenceforward he was under his special care.
Whist the expedition was preparing, Cruz spent a couple of days in an unsuccessful attempt to get to the summit of the volcano in the vicinity of Antuco, which he describes as being then in continual action, and at times burning so strongly as to be visible from a very considerable distance: but he was stopped, and obliged to turn back, by a heavy fall of rain and snow, considered by the Indians as an interposition of the Deity to prevent the examination of a region which they held it to be forbidden to mortals to approach.