Civil wars broke out between the Buenos Aires oligarchy and local military chiefs in the gaucho provinces and soon hurled Posadas from power. He was succeeded by Alvear, but the commanders of the armies refused to recognise the latter's authority and an insurrection in Buenos Aires itself drove him, too, into exile. One military dictator succeeded another, while the provinces more and more ignored the Buenos Aires pretensions to hegemony. The frail fabric of the confederation fast crumbled into fragments. With the end of the Napoleonic wars re-enforcements began to arrive from Spain, and the royal arms were again victorious and threatened to wipe out the distracted Republic. Rondeau, one of the generals who had helped depose Posadas and Alvear, had been rewarded with command of the army of the north. Disregarding the experience of his predecessors, he made the third great effort to conquer Bolivia and strike at the heart of Spanish power in Peru by the overland route. His campaign ended with the crushing defeat at Sipe-Sipe. Considerable Spanish forces followed him down into the Argentine plains, but, as San Martin had predicted, the gaucho cavalry under Guemes were able to keep back their advance. Belgrano and Rivadavia had been sent to Spain in 1813 to try to arrange terms on the basis of autonomy, or the making of Buenos Aires a separate kingdom under some member of the Spanish family. They were informed that nothing except unconditional submission would be accepted, and they were then ordered to leave Madrid. Scheme after scheme was presented in Buenos Aires, discussed, and abandoned. Belgrano wanted to make a descendant of the Incas emperor of South America. Others wished to offer submission to Great Britain in return for a protectorate. The English government rejected the overtures. A more popular idea was to elect a monarch from the Portuguese Braganza family, then reigning in Brazil. The only definite result of all these confused negotiations was a formal declaration of independence made on the 9th of July, 1816, by a Congress at which most of the provinces were represented, and which met in the city of Tucuman. Many of the members had no hope of being able to enforce such a declaration. However, it cleared the way for obtaining foreign help, and negotiations were continued with a view to inducing some European prince to accept the throne. Artigas, the independent military chieftain of Uruguay and Entre Rios, attacked in 1813 the Missions to the left of Upper Uruguay which the Rio Grande Brazilians had seized twelve years before. He was defeated by the troops of John VI., who followed him into Uruguay proper and in 1816 captured Montevideo. Though the Buenos Aireans had been compelled to concede Uruguay's independence, this movement excited among them an intense jealousy of the Portuguese. The scheme for a Braganza monarch at once became unpopular and impracticable.