Dorrego succeeded him, but in reality the Republic was showing a strong tendency to split up, and Lopez in Santa Fé, Ibarra in Santiago, Bustos in Cordoba, and Quiroga in Cuyo, possessed almost as much power as Dorrego at Buenos Aires. However, with the help of several of these men, he succeeded in ending the war by a compromise which left Uruguay an independent state. Argentina was thus free to devote herself to domestic warfare.
Lavalle was now the head of the Unitarians, and he succeeded in expelling Dorrego from Buenos Aires. The latter fled to his estates and raised a body of adherents, but was captured and shot by Lavalle. The death of Dorrego cleared the way for a man who was destined to have a much longer political life than is usual in South America, and also to fill a much larger space in the eyes of the world. That man was Juan Manuel Rosas.
Darwin records that he and the well-wishers of Argentina were looking with satisfaction and hope at the vigorous measures and rapid advances of this remarkable man, and he also adds in a note written years afterwards that these hopes had been miserably disappointed. Rosas was a rich man, and from his earliest days had been engaged in cattle-raising on the southern Pampas. In this hardy open-air life he had greatly distinguished himself by his boldness and skill in riding, and was the idol of hundreds of half-savage Gauchos. He was not endowed with signal abilities, but he was a hard, practical man, full of audacity and little troubled by scruples. He was now the chief of the Federalists, but at first there seemed little prospect that he would be able to make head against Lavalle. The latter led an army to attack his enemies in Santa Fé, while General Paz marched upon Cordoba, and at the same time they sent some veteran troops to operate against Rosas in the south. But these were overthrown by the hardy horsemen of Rosas, and he came to the rescue of the Federalists. General Paz had captured Cordoba, and defeated Quiroga with heavy slaughter, but Rosas' weight turned the scale. He marched to Buenos Aires, and in June, 1829, Lavalle, who had become involved in a dispute with the French Minister, was glad to resign and leave the country. His successor, Viamont, was a puppet of Rosas.