Casares became a vocal opponent of Buenos Aires Province Governor Juan Manuel de Rosas, and he was jailed for a time. Following the strongman's fall at the 1852 Battle of Caseros, he entered politics, and in 1857, was elected to the Provincial Legislature.
Casares became a vocal critic of Buenos Aires Province Governor Juan Manuel de Rosas, and he was imprisoned for a time. After the strongman's downfall at the 1852 Battle of Caseros, he entered politics and was elected to the Provincial Legislature in 1857.