In spite of his conservative and devout Catholic upbringing, the young Pestana was an avid reader of the French philosopher Auguste Comte and joined, much to the chagrin of his father, the Brazilian republican and positivist movement, which would contribute to overthrow the monarchy in 1889.

A few months after graduation, Pestana accepted an invitation to move to Rio Grande do Sul in order to work as an engineer of the State commission responsible for the Porto Alegre-Uruguaiana railway connection.

The job would acquaint him with the peculiar politics of Rio Grande do Sul within the newly founded Brazilian Republic, uniquely fashioned by the Comte-inspired dictatorship of Governor Júlio de Castilhos.

The settlement was facing then a severe crisis caused by bad management and by quarrels among the more than ten ethnic groups present in the region (mainly Germans, Italians, Portuguese, Poles, Afro-Brazilians, Austrians, Swedes, Spaniards, Latvians and Arabs).

Upon his arrival in early 1899, Pestana gathered the leaders of all immigrant communities in a place currently known as Union Hill (Alto da União) and managed to pacify them.

He rationalized the policy of rural settlements, favoring families with previous experience in agriculture, and attached priority to investments in education and infrastructure, helping to diversify the economy of Ijuí'.

[12] Elected again to the National Congress of Brazil on April 28, 1928, and on March 1, 1930, Pestana did not engage in the Brazilian Revolution of 1930 in spite of his friendship and political comradeship with President Getúlio Vargas.

He provided a decisive contribution to the development of Ijuí and Northwestern Rio Grande do Sul, stressing the importance of robust public policies on infrastructure and education.