He placed himself under the orders of general Urquiza, but it is not known if he fought at the Battle of Caseros where Rosas was defeated. He supported Urquiza's policies in Buenos Aires, and was in charge of a federal battalion. He was still very much hated by the Unitarian Party who were taking control of the city, and who would depose governor Vicente López y Planes in the September revolution which Casanovas did not get to see. He was assassinated in 1852 in a Buenos Aires street by a unitarian party member (note: a political movement, not related to the Christian church), who still believed he was guilty of the treason of 1841.