On March 9, 1812, occurred an important event in the history of Argentina. On that date Jose de San Martin arrived in Buenos Aires in the British frigate _George Canning_. With him came Carlos Alvear and Matias Zapiola, whose names were likewise destined to become famous in the annals of the Republic. On their arrival there was established in Buenos Aires a branch of the now important secret society originally founded in London, the "Gran Reunion Americana." This branch was christened the "Logia de Lautaro," and exercised much influence on the affairs of the revolution. San Martin was empowered by the Government to raise a force of horse-grenadiers, which subsequently became famous. In this regiment was Alvear in the capacity of Sargento Mayor, and Zapiola as Captain. There was plenty of work for the newly-constituted forces. San Martin's regiment was employed, in the first place, in the endeavour to restrain the river-raiding expeditions which the Royalist fleet was undertaking from its base at Montevideo. The mischief effected by these incursions to the patriot forces was very great. On February 3, 1813, however, San Martin dealt the Spaniards a severe blow in the neighbourhood of Rosario. Here he surprised a landing-party and defeated it utterly. This was San Martin's first victory, and it very nearly proved his last, for he had his horse shot under him and all but lost his life. While this was going on in Argentina, the fortunes of war in Peru had again veered from a favourable to a perilous condition. On October 1, 1813, the Argentine army was badly defeated at Vilcapuyo, and in the same year it was again defeated at Ayouma. On this the Spaniards, seeing that their star was again in the ascendant, resumed possession of Chuquisaca and Potosi. San Martin was now sent to take charge of operations in Peru. On the Argentine side the campaign had in one sense degenerated, since the diminished numbers of the Republican forces now restricted them to guerilla fighting. This species of warfare, as a matter of fact, suited the hardy Argentines admirably, and under such brilliant leaders as Martin Guemes, Ignacio Warnes, and Juan Antonio Alvarez de Arenales, their feats had kept the Royalist forces fully occupied. San Martin, on his arrival, immediately realized the advantages of this species of resistance, and encouraged it to the utmost. By this means alone was an invasion staved off.