Elsewhere in southern Spanish America a brilliant feat of arms brought to the fore its most distinguished soldier. This was Jose de San Martin of La Plata. Like Miranda, he had been an officer in the Spanish army and had returned to his native land an ardent apostle of independence. Quick to realize the fact that, so long as Chile remained under royalist control, the possibility of an attack from that quarter was a constant menace to the safety of the newly constituted republic, he conceived the bold plan of organizing near the western frontier an army--composed partly of Chilean refugees and partly of his own countrymen--with which he proposed to cross the Andes and meet the enemy on his own ground. Among these fugitives was the able and valiant Bernardo O'Higgins, son of an Irish officer who had been viceroy of Peru. Cooperating with O'Higgins, San Martin fixed his headquarters at Mendoza and began to gather and train the four thousand men whom he judged needful for the enterprise. By January, 1817, the "Army of the Andes" was ready. To cross the mountains meant to transport men, horses, artillery, and stores to an altitude of thirteen thousand feet, where the Uspallata Pass afforded an outlet to Chilean soil. This pass was nearly a mile higher than the Great St. Bernard in the Alps, the crossing of which gave Napoleon Bonaparte such renown. On the 12th of February the hosts of San Martin hurled themselves upon the royalists entrenched on the slopes of Chacabuco and routed them utterly. The battle proved decisive not of the fortunes of Chile alone but of those of all Spanish South America. As a viceroy of Peru later confessed, "it marked the moment when the cause of Spain in the Indies began to recede." Named supreme director by the people of Santiago, O'Higgins fought vigorously though ineffectually to drive out the royalists who, reinforced from Peru, held the region south of the capital. That he failed did not deter him from having a vote taken under military auspices, on the strength of which, on February 12, 1818, he declared Chile an independent nation, the date of the proclamation being changed to the 1st of January, so as to make the inauguration of the new era coincident with the entry of the new year. San Martin, meanwhile, had been collecting reinforcements with which to strike the final blow. On the 5th of April, the Battle of Maipo gave him the victory he desired. Except for a few isolated points to the southward, the power of Spain had fallen.