Jovanović was born in 1914 in Valjevo, Central Serbia, related to an extended family of landowners and merchants. He graduated from high school there, enrolling the Faculty of Philosophy at the University of Belgrade. However, before completing his studies, Žikica, like so many other idealists across Europe, volunteered to help the Spanish Republic rebuff a Fascist Coup launched in the Summer of 1936. Whilst in Spain he fought with some distinction in the Spanish Civil War, and became a highly respected guerrilla warfare specialist and combatant of the Madrid University City Battle between the Republican volunteers and the Spanish Army of Africa. He stayed on fighting at the head of the Balkan Volunteer Brigade in a number of campaigns such as Battle of the Ebro and Teruel until the fall of Barcelona in 1939, with the tragic collapse of the Republic.