Five thousand Peruvian troops left Callao in May for the South under General Santa Cruz, with Colonel Gamarra as chief of the staff. For the first time Peru had an army of her own, commanded by Peruvian generals. Before leaving, Santa Cruz presented himself to Congress and swore to return triumphant or to die. He did neither the one thing nor the other.
Santa Cruz showed more activity than Alvarado had done. On the 17th June the convoy reached Arica. On that same day Canterac, with an army of 9,000 men, rushed down from the Highlands and captured Lima. The expedition was thus isolated, but the move was a false one on the part of the Royalists.
Bolívar did not share in the general confidence, he was more clear sighted than most others, as is seen in a notable letter which he wrote at this time to General Sucre. He had concentrated his forces at Guayaquil, and on hearing of the disasters of Torata and Moquegua, before signing the treaty of which we have already made mention, he at once sent off an expedition of 3,000 men under Sucre, with instructions to gain possession of the fortresses of Callao at any cost. Sucre, whom he called “his right arm,” was also named minister plenipotentiary to Peru, and was sent to prepare the way for the accomplishment of the secret designs of the Liberator, who saw that Peru would soon be in a condition to welcome him as her saviour.
The occupation of Lima by the Royalists was a mistake, it gave them no military advantage while Callao and the ocean were held by the Patriots. The Government fled to Callao, and the army collected under shelter of the guns of that fortress. Sucre was made general-in-chief. Congress dispersed; some of the members went over to the enemy; but a minority, who were hostile to Riva-Agüero, kept together, and sent for Bolívar on the 19th June, 1823, giving him the title of Generalissimo and ample powers for the salvation of the country. Riva-Agüero retained the title of President, but was sent out of the way to Trujillo.
Bolívar accepted the invitation, saying that “for a long time his heart had yearned towards Peru.” Pending his arrival Sucre exercised his powers as his representative; the secret wish of Bolívar was accomplished, he was master of Peru.
The Viceroy soon perceived the mistake he had made, and recalled his army from Lima. On the 16th July Canterac evacuated the city, and returned to the Highlands unmolested. On the 20th Sucre sailed southwards with 3,000 Columbians and Chilians and a squadron of Peruvian cavalry, leaving an army of Peruvians, Argentines, and Columbians at Lima with orders to occupy Jauja and secure the line of the Apurimac. His intention was to combine the movements of the three armies, with Arequipa as the base of his operations, and to advance on Cuzco with 8,000 or 12,000 men, but when he reached the south coast Santa Cruz was already far inland. He then landed at Quilca and marched on Arequipa; but the same day Santa Cruz had fought a battle of doubtful result on the borders of Lake Titicaca.
Santa Cruz had changed the plan. Instead of keeping his army together he had divided it into two columns, directed against Upper Peru. With the first he landed near Ilo, and advanced to Moquegua, while the second, under command of Gamarra, landed at Arica, and occupied Tacna. Here he remained till the middle of July, awaiting the Chilian contingent; but as it did not come he, on the 13th July, ascended the Cordillera, crossed the Desaguadero by the bridge of the Inca without opposition, and on the 8th August occupied the city of La Paz. Gamarra at the same time marched by the Tacora road, crossed the Desaguadero lower down, and occupied the city of Oruro, which is about 170 miles from La Paz.
Olañeta, who was retreating towards Potosí with 1,500 men, was almost surprised by Gamarra, of whose movements he knew nothing, and withdrew to the South. Gamarra was then joined by Lanza, the Guerilla chieftain, with 600 men, and learned that Urdininea, with the Argentine division, was advancing from Salta; but he lost the opportunity of destroying Olañeta, which was part of the plan of Santa Cruz, by remaining inactive at Oruro.
Santa Cruz, hearing that La Serna was concentrating his scattered divisions at Puno, then turned back to cover the line of the Desaguadero, and stationed himself on the left bank at the bridge of the Inca. Valdés advanced against him with 2,000 men, but finding the bridge was defended by artillery, he withdrew to the town of Zepita. Santa Cruz crossed the bridge and went after him, and overtook him in a strong position between the mountains and the lake of Titicaca. By a feigned retreat he drew Valdés into the plain, where two Peruvian squadrons cut the Royalist horse to pieces, but the attack upon the infantry was less successful, and night put a stop to the action. Both sides claimed the victory, but Valdés retreated, and soon after Santa Cruz returned to his position on the Desaguadero. This was the first and last battle of the expedition.
La Serna joined Valdés at Zepita, and crossed the Desaguadero with 4,500 men. Santa Cruz retreated before him, and on the 8th September joined Gamarra to the south of Oruro. He then manœuvred to prevent a junction between La Serna and Olañeta, who was returning from Potosí with 2,500 men, but La Serna by a flank march over the heights succeeded in effecting the junction on the 14th September. Santa Cruz thought himself lost, and without attempting to bring on an action in which the chances would have been in his favour, retreated precipitately. The retreat soon became a flight, arms and baggage were thrown away, and he recrossed the Desaguadero utterly routed, without fighting and without even seeing an enemy. He left a company of infantry with two guns to defend the bridge, who capitulated to the Royalist vanguard at the first summons. Barely 1,000 men reached the coast, and the Chilian contingent, which just then arrived, returned at once to their own country.