Bolivar waited in vain for the expected invitation to come with his veterans. The leaders in Peru did not propose to jeopard their own supremacy. They thought they were strong enough to whip the Spaniards by themselves, and made great efforts to drill and equip an efficient army. By the end of the year four thousand men under the command of Alvarado were sent to the southern coast to make an attempt to reach Lake Titicaca and thereby get between the Spanish armies. It failed before the astonishing energy of the Spanish general, Valdez, who by forced marches reached the pass which the Peruvians were trying to climb, and taking up a strong position, beat them back with great slaughter. Alvarado retreated, but was caught by Valdez and completely routed; hardly a third of the army escaped to the seashore. The news of this defeat brought about a change of government at Lima. A revolution, headed by the principal officers, made Riva Aguëro, the leader of the Peruvian liberals, president, while General Santa Cruz, a Bolivian, received chief command of the forces, in place of Arenales. Word was sent to Bolivar that his offer of help would be accepted; and another Peruvian army was recruited. Before the six thousand men promised by Bolivar had arrived, the Peruvians had regained confidence. With the aid of a London loan, the patriots got seven thousand soldiers ready for service, and in May, 1823, five thousand men under the command of Santa Cruz sailed from Callao for southern Peru. This time they advanced so promptly that the Spanish generals could not get to the passes in time to dispute the way. Santa Cruz entered La Paz and defeated the first army which came against him. But the two main Spanish bodies hastened up from Cuzco and Charcas, outmanoeuvred Santa Cruz, united their forces, and routed his army in a panic, not a fourth ever reaching the seaboard.
Shortly after Santa Cruz's departure on this ill-fated expedition, Sucré arrived at Lima with the first instalment of the promised Colombian auxiliaries. The Spanish general, Canterac, had concentrated a large army at Jauja and descended on the capital; Lima was denuded of Peruvian troops; the government helpless against the Spaniards or Sucré. The Colombian was made commander-in-chief, and retiring to the fortifications of Callao before Canterac's overwhelming numbers, procured Riva Aguëro's deposition and the nomination of one of his own tools as nominal president, while he sent off an urgent message to Bolivar to come in person. Canterac, after holding Lima for a few weeks, went back to the mountains, and Bolivar himself landed at Callao on the 1st of September, almost at the very moment when Santa Cruz's army was getting involved in that snarl out of which it never extricated itself. The news of its destruction left Bolivar undisputed master of the situation, and in February the submissive rump of the Peruvian parliament conferred upon him an absolute dictatorship. He now devoted all the wonderful energy with which nature had endowed him to preparation for a campaign which he meant to be final; and united ten thousand men under his command, two-thirds of whom were Colombian veterans and the rest Peruvians, Argentines, and Chileans who fought for the sheer love of fighting. His officers were the pick of South America, men who had proven their bravery and skill on all the hundred battle-fields from Venezuela to Chile. With such a force he did not hesitate to attack the Spaniards, although the latter were nearly twice as numerous.