Flores Magón, published a liberal journal in which they issued a call to revolution. With this publication came an unexpected ally – Francisco Madero, who was the son of a wealthy hacienda owner. Madero began to publicly denounce Díaz and tour the country to talk of free elections, democracy and social change. Because of harassment by Díaz, he joined the Flores Magón brothers and other Mexican liberals in El Paso, Texas, where he continued to fuel the fires of revolution from afar. In 1910, with the issuance of the Plan of San Luis Potosi by Madero, Mexico, for the first time in its history, was thrust into a full-blown revolution. Because of the writings of Madero, the Flores Magón brothers and other Constitutionalists (although they were still just labeled liberals), people from every social class and from every ethnic background rose up to answer the revolution's call. During this time not only did leaders such as Zapata and Villa arise, but many Constitutionalists, most of them lawyers, journalists or leading intellectuals, also gained in power and popularity. By the time Díaz agreed to step down and Madero was elected president, the Constitutionalists had gained a power base in most of Mexico's urban population centers, which were mainly located in the center of the country. Zapata held most of the southern regions where the people of indigenous descent were located, and Pancho Villa led the northern areas dominated mostly by ranchers and miners. Rise of Venustiano Carranza Madero's presidency proved to be short-lived, as he alienated almost all of his supporters by refusing to enact land reforms and developing weak and unsatisfactory programs for social change. General Victoriano Huerta eventually staged a coup that overthrew Madero and installed himself as president. His authoritarian and brutal methods of ruling, however, soon united the Constitutionalists, who were now being led by Venustiano Carranza, with Zapata and Villa in overthrowing Huerta. Carranza replaced Huerta as president of Mexico in 1913 after the U.S. intervention at Veracruz forced Huerta to abdicate. In 1914, all the leaders of the Revolution met at the Convention of Aguascalientes in order to decide on a plan of action for the future. The Convention was quickly reduced to arguments, as Carranza could not agree with Zapata and Villa, who thought he was too power-hungry and not a true leader of the revolution. An especially sensitive subject was the issue of