In 1926, the fourth and final dissent arose within the Paulista Republican Party (PRP). The dissidents were led by Dr. José Adriano de Marrey Junior. He founded the Democratic Party (PD), which, among other reforms, advocated a program of higher education as well as the overthrow of PRP power. This political crisis originated within the Freemasons, chaired by Dr. José Adriano de Marrey Junior. As such, São Paulo was divided during the elections of 1930.

During the Old Republic (1889–1930), the "coffee with milk policy" was enforced, which was supported by politicians in São Paulo and Minas Gerais. They alternated in the presidency but were not necessarily Paulistas or Mineiros or their nominees. However, in early 1929, Washington Luís indicated Júlio Prestes to be his successor in a move to be supported by presidents of 17 states. Only three states denied supporting Prestes: Minas Gerais, Rio Grande do Sul, and Paraíba. Politicians from Minas Gerais expected Antonio Carlos Ribeiro de Andrada, then the governor of the state, to be named by Washington Luís as presidential candidate.

The greatest sign of wear of the Old Republic was overproduction of coffee during the crisis of 1929, fueled by the government through constant price increases.

The "coffee with milk policy" came to an end and the opposition began articulating a position against the 17 states to elect Júlio Prestes as President. Minas Gerais, Rio Grande do Sul, and Paraíba joined the political opposition from several states, including the Democratic Party of São Paulo, to oppose the candidacy of Júlio Prestes, forming the Liberal Alliance in August 1929.

On September 20 1929, the Liberal Alliance launched their candidates for the presidential elections: Getulio Vargas as candidate for President and João Pessoa Cavalcanti de Albuquerque as candidate for Vice President.

The elections were held on March 1, 1930 and gave victory to Júlio Prestes, who received 1,091,709 votes against 742,794 given to Getúlio Vargas. Notoriously, Vargas had almost 100% of the votes in Rio Grande do Sul.

The conspiracy suffered a setback in June with Luís Carlos Prestes. A former member of the "Tenentismo" movement, Prestes adopted the ideas of Karl Marx and began to support communism. After some time, this led to the failed attempt at a communist overthrow by the Liberal Alliance.Soon thereafter, another setback to the conspiracy occurred as Siqueira Campos died in a plane crash.

On July 26, 1930, João Pessoa was assassinated by João Dantas in Recife for political and personal reasons. This became the flashpoint for armed mobilization. João Dantas and his brother-in-law & accomplice, Moreira Caldas, were found beheaded in their cell at the House of Detention (today the House of Culture) in 1930.

The 1930 revolution began in Rio Grande do Sul on October 3 at 5:25pm. Osvaldo Aranha telegraphed Juarez Távora to communicate the beginning of the Revolution. It spread quickly through the country. Eight state governments in the northeast of Brazil were deposed by revolutionaries.

On the 10th of October, Vargas launched the manifesto, "Rio Grande standing by Brazil" and left, by rail, towards Rio de Janeiro, the national capital at the time.

On October 12 and 13, the Battle of Quatiguá took place (possibly the biggest fight of the revolution), although it has been little studied. Quatiguá is located to the east of Jaguariaíva, near the border between São Paulo state and Paraná.

The battle did not occur in Itararé since the generals Tasso Fragoso and Mena Barreto and Admiral Isaiah de Noronha ousted Washington Luís on October 24 and formed a joint government.

At 3 pm on November 1, 1930, the junta handed power and the presidential palace to Getulio Vargas, ending the Old Republic and knocking down all state oligarchies except from Minas Gerais and those from Rio Grande do Sul. At the same time, in downtown Rio de Janeiro, the gaúcho soldiers fulfilled the promise of tethering horses to the obelisk on Rio Branco Avenue, symbolically marking the triumph of the Revolution of 1930.

One of the biggest mistakes of the 1930 revolution was delivering the states to inexperienced administrative lieutenants. The unpreparedness of the lieutenants to govern was terminated early in 1932 by one of the top lieutenants, Lieutenant John Cabanas, who had participated in the 1924 revolution.