Ramírez and Edelmiro Farrell. During this period, the Argentinian unions, mainly the socialists and the syndicalists as well as a few communists, formed an alliance with a group of young army officials led by the Colonel Juan Perón. This alliance constituted the successful nationalist labor movement which prevailed by winning popular support from the working class and which was given the name "Peronism". This period was characterized by extreme polarization of the social classes and led to the formation of a large social block that was strongly anti-Peronist and made up mostly of the middle class and upper class. Economically, the Revolution of '43 saw the continuation of the policy of Import Substitution Industrialization. The dictatorship ended with a call for a democratic elections on February 24, 1946, which all the sections of society accepted as perfect. Juan Domingo Perón won the elections and assumed the presidency on June 4, 1946. Perón would later be overthrown by the military in 1955, before he finished his second term. Coup of 16–23 September 1955 The so-called Revolución Libertadora was a transitional military dictatorship, brought about by a coup d'état which overthrew the president Juan Domingo Perón and lasted between 16 and 23 September 1955. On the last day of this period, the leader of the insurrection, Eduardo Lonardi, was sworn in as president and congress was dissolved. On the following day, he designated Admiral Isaac Rojas as vice president. During the Revolución Libertadora, the military government created a Civilian Advisory Board composed in large part of the political parties of the Radical Civic Union, the Socialist Party, the National Democratic Party, the Christian Democratic Party, and the Democratic Progressive Party. The group behind the coup was divided in two parts: a Catholic-nationalist part led by General Eduardo Lonardi, who took charge of the government initially, and a liberal-conservative part led by General Pedro Eugenio Aramburu and Admiral Isaac Rojas. The latter group ended up gaining power and executing another coup, replacing Lonardi with Aramburu as president. The dictatorship in power imposed a ban on Peron's Justicialist Party and began the persecution of its sympathizers, policies that would be maintained by successive governments over the following 18 years. The government also took over the unions. In actions that were unprecedented in the modern history of Argentina, it executed its opponents by firing squad, sometimes in public and sometimes clandestinely. The government appointed civilians