ongoing issue in Mexican history since the Catholic Church sought to retain its role in this sphere, while liberals have sought to undermine the Church's role. Since the 1940s, Catholic universities have re-emerged. Unionized school teachers have become a powerful force in the late twentieth and early twenty-first-century Mexican politics. Post-Independence Era, 1821–1850 When Antonio López de Santa Anna put his Liberal vice president Valentín Gómez Farías in charge of running the government, the vice president created in 1833 a public education system. This preceded the establishment of a Ministry of Public Education. This reform was short-lived, but with the Liberal Reform in the mid-nineteenth century, a normal school for teacher training was established. The Liberals push for public education awaited the end of the War of the Reform and the ousting of the French Empire in Mexico (1862–67). The restored Republic of President Benito Juárez reaffirmed the Liberals principle of separation of church and state, which in the educational sphere meant supplanting the Catholic Church by the Mexican state. Primary education in Mexico was henceforth to be secular, free of fees and tuition, and obligatory. Reform era, 1850–1876 A key figure in higher education in Mexico was Gabino Barreda, who chaired Juárez's commission on education in 1867. Barreda was a follower of French intellectual Auguste Comte who established positivism the dominant philosophical school in the late nineteenth century. The Juárez government created a system of secondary education, and a key institution was the National Preparatory School (Escuela Nacional Preparatoria), founded in 1868 in Mexico City, which Barreda directed. Education at the Preparatoria was uniform for all students and "designed to fill what José Díaz Covarrubias identified as the traditional void between primary and professional training." Porfiriato, 1876–1910 During the Porfiriato (1876–1910), the era of Porfirio Díaz's presidency, secular, public education was a priority for the government, since it was seen as a vehicle for changes in behavior that would benefit the government's commitment to progress. The number of schools expanded and the federal government expanded centralized control. Municipal governments had to yield control to state governments, and the federal bureaucracy for public schooling was established under the Ministry of Education, a cabinet-level position. More money was spent on public schools in this era, increasing faster than other public expenditures. Public schooling was part of Mexico's project of modernization, to create an educated workforce. Those overseeing schools sought to instill