By 1820, provinces throughout the region centralized their power by replacing the cabildos with provincial governments. Buenos Aires, no longer serving the administrative role of the Viceroyalty, turned its substantial resources towards implementing liberal polices within its borders. Led by Bernardino Rivadavia, the province enacted legislation supporting universal male suffrage, freedom of the press, religious toleration, tax reform, European immigration, floating interest rates, and public education. To a lesser extent, many of the same acts were carried out in the interior, although most included a tariff tax in imports to protect local industry.
A national congress assembled in 1824 considered the issue of national unity. They passed a law that provinces would govern themselves until a national constitution could be signed. As the United Provinces, they elected the liberal Rivadavia to the presidency of the republic. He quickly implemented many of the liberal measures that were in place in Buenos Aires. These policies, particularly those against the church, turned provincial opinion against Rivadavia.
In 1827 Rivadavia resigned the presidency, effectively ending national and liberal governance for a generation. Into the void stepped Manuel Dorrego as the newly elected governor of Buenos Aires. A federalist, Dorrego nonetheless provided a moderating influence upon the tensions between the two rival groups.
He maintained many of the liberal policies enacted by Rivadavia in Buenos Aires.
Sadly, the Unitarios believed that federalism could be defeated only if they removed the federalist leaders. The opportunity arose to attack Dorrego when he signed a peace treaty with Brazil that ended the war over the future of the Banda Oriental (now Uruguay). One of the divisions of the Argentine army, which supported the Unitario cause, mutinied, captured Dorrego in battle, and summarily executed him without trial in 1828.
This act outraged the public, leading the rise of Juan Manuel Rosas.