Hugo Ballivián Rojas (7 June 1901 – 15 July 1993) was a Bolivian politician and military officer who served as the de facto 44th President of Bolivia from 1951 to 1952. A career military officer, he was Commander of the Bolivian Armed Forces when President Mamerto Urriolagoitía called upon him to take over as extra-Constitutional chief executive in order to prevent the swearing-in of the reform-minded President-elect, Víctor Paz Estenssoro. This was a self-coup that became popularly known as the Mamertazo. Installing himself in the Palacio Quemado, Ballivián was the oligarchy's last hope to "turn back the hands of the clock," but the situation was apparently beyond repair. Despite declaring a nationwide curfew and exiling and imprisoning a number of opposition leaders, the demonstrations,