The first six months of 1821 were consumed in these fruitless negotiations, and by this time the position of the Spaniards at Lima had become untenable. It was necessary for them to retire to the plateau, where the sturdy natives furnished a supply of excellent recruits and the mines, fields, and pastures would maintain an army. On July 6, 1821, La Serna evacuated the capital and retired to Jauja, leaving a well-provisioned garrison at Callao against the hoped-for arrival of a fleet from Spain. Even then a dozen well-fought frigates might have undone all San Martin's work and changed the fate of South America. Three days later the Argentine general entered the city, and on the 28th of July, 1821, Peru was proclaimed an independent republic, with San Martin as temporary dictator under the title of Protector. During the rest of the year he was occupied with trying to secure the adhesion of the whole coast, and made no effort to undertake the redemption of the interior. When the Frenchman Canterac, the most enterprising of the Spanish commanders, made a descent on Lima, San Martin merely maintained the defence, being well assured that the enemy must soon retire on account of want of provisions. But he found himself hampered in consolidating coast Peru by the fact that he was a foreigner. The Peruvians were jealous and suspicious, and he feared that troops recruited among them might turn their arms against him, while his Argentine officers regarded the country as their own property, and monopolised the positions of honour and profit to which the Peruvians thought themselves more justly entitled. Matters remained virtually at a standstill until the summer of 1822. San Martin had been unable to make his position stable enough to justify his devoting himself to military operations, nor had he succeeded in gathering and equipping an army with which he was willing to undertake a decisive campaign. Canterac even took the offensive, although he made no effort to re-occupy permanently the coast plain. Outside help was necessary, and San Martin, despairing of obtaining it from Chile or the Argentine, turned his eyes to the north. Bolivar's battles of Boyaca and Carabobo had redeemed northern Granada and Venezuela in 1819 and 1821, and he was now advancing toward Quito to complete the expulsion of the Spaniards from that viceroyalty. With a force of Colombians Sucre went to Guayaquil by sea and climbed to the Ecuador plateau. Defeated and driven back on his first attempt, he was reinforced by a division sent by San Martin, and renewed the effort with better success. Although Bolivar had in the meantime been checked in his southward march on Quito by the loyalists of southern Colombia, Sucre alone destroyed the Spanish army which had held Ecuador for so many years. The battle of Pichincha, fought in May, 1822, left Bolivar and Sucre free to employ their numerous and well-disciplined troops in completing the liberation of Peru and Bolivia.