Excerpts from Books and Wikipedia
"Colonel Ignacio Comonfort became president in 1855 after a revolt based in Ayutla overthrew Santa Anna. Comonfort was a moderate liberal who tried to maintain an uncertain coalition, but the moderate liberals and the radical liberals were unable to resolve their sharp differences. During his presidency, the Constitution of 1857 was drafted creating the Second Federal Republic of Mexico. The new constitution restricted some of the Catholic Church's traditional privileges, land holdings, revenues and control over education. It granted religious freedom, stating only that the Catholic Church was the favored faith. The anti-clerical radicals scored a major victory with the ratification of the constitution, because it weakened the Church and enfranchised illiterate commoners. The constitution was unacceptable to the clergy and the conservatives, and they plotted a revolt. With the "Plan of Tacubaya" in December 1857, Comonfort tried to regain the popular support from the growing conservative pro-clerical movement. The liberals failed, however, as conservative General Félix Zuloaga succeeded in a coup in the capital in January, 1858." [Wikipedia]