In March, 1816, a detachment of the grenadiers, under Aldao, made a successful reconnaissance by the Uspallata Pass, of the Royalist positions on the western slopes of the Andes, and brought back much useful information; but true to his principle of concealing his plans, San Martin reported to Government that the central passes were so well defended that the only practical course was by those to the south of Mendoza; and also that advanced field works were necessary about Uspallata, in order to secure the Province of Cuyo as the base of operations. This procured him a further much needed supply of guns.
In April General Balcarce, the hero of Suipacha, succeeded Alvarez as Provisional Director, and San Martin was thenceforward much better supported by the central power; military supplies were sent to him on a much more liberal scale than under the previous administration.
The power of the Lautaro Lodge had fallen with Alvear, but the society still existed, and San Martin now established a branch in Mendoza, in which the principal leaders of the Chilian refugees, and many of the foremost men of Cuyo, were affiliated.
At this time he received most efficient assistance from his friend Don Tomas Guido, who had first met him in London, and who had afterwards in Tucuman learned from him something of his ideas in regard to the conduct of the war. Guido drew up a memorial and presented it to the Supreme Director, in which he warmly supported the idea of attacking Peru by way of Chile; and his aid became still more efficacious when the meeting of the Congress of Tucuman, a few weeks later on, placed the administration of affairs in new hands.
