Recalling the 155 years of existence, we will emphasize to the most important stages of the city. Among the antecedents of the foundation, it must be accounted that the oldest establishment in the City was the Military prison of Old Monclova. A site created by the Virreinal Government of the New Spain, to defend the first towns and missions of Coahuila, from the attacks of the natives in March of 1773, installed by the Spanish, Inspecting Commander of Military prisons, Don Hugo ÓConnor, to give fulfillment to the relocation of some Military prisons, but by not known causes did not do it in its totality with the Military prison of Santiago of the Monclova, what today is the city of Monclova, because it decided to leave only the half of the troops and the rest was relocated near the Rio Grande in the environs of the hill of El Moral, in the right margin of the San Rodrigo River, several kilometers of the confluence of this River with the Bravo, closely together of the present Congregation of El Moral. But also by unknown causes, ÓConnor called this place Military Prison of Old Monclova, instead of New Monclova or another similar or different name, considering the upcoming of its foundation in relation to the Military prison of Santiago of the Monclova, done 96 years before.

This military installation fulfilled the objective for which it was created. Between the years 1835 to 1850, this area was put under a triple aggression: The one of the revolutionaries, the one of the natives and the one of the texan rebels whom they looked to consolidate their independence.

The most important point in the military order and customs, was the Military prison of San Juan Baptist of the Rio Grande, what today is Villa of Guerrero, whose customs was the only one recognized officially from the completion of what was called free zone, although the term customs was used, was more allegorical than real, because smuggling was practiced on daily basis.

When the 1847 war ended, where we lost half of our territory, the Military prisons went to take part of the new Military Colonies and between the Colony of Guerrero and the one of Old Monclova, a road existed that passed by a site, to which people called Piedras Negras Passage. A practicable ford that could compete with the Passage of France, in what today is Villa of Guerrero; it was called by this name (Piedras Negras, “Black Stones”), by the great amount of coal that existed in the surface. This place began to be one of the most used for smuggling, but during the war with Texas was sporadically used.

The Piedras Negras Passage began to receive visitors in 1849, the same year when the Fort Duncan was starting being built, a military facility that became over the time the City of Eagle Pass, in the State of Texas. The presence of the soldiers in the Fort initiated a commercial blossoming in the border region which occurred to the margins of the legality, because customs didn’t exist in the Piedras Negras Passage, only 40 kilometers away from the Fort.