The northern part of Mexico, in 1788 and for many previous years had been constantly ravaged by the wild Indian tribes that ranged across the whole frontier from the western limits of Sonora to the Gulf of Mexico. Immense sums were squandered in the support of garrisons or the maintenance of numerous officers, whose duty it was to hold these barbarians in check. But their efforts had been vain. The fine agricultural districts of Chihuahua, New Leon, New Mexico and even in parts of Texas, had attracted large numbers of adventurous pioneers into that remote region; yet no sooner did their fields begin to flourish and their flocks or herds to increase, than these savages descended upon the scattered settlers and carried off their produce and their families. Whenever the arms of New Spain obtained a signal victory over one of these marauding bands, the Indians would talk of peace and even consent to bind themselves by treaties. But these compacts were immediately broken, as soon as they found the country beginning to flourish again, or the military power in the least degree relaxed.
Flores appears to have understood the condition of the northern frontier and the temper of the Indians. He did not believe that treaties, concessions or kindness would suffice to protect the Spanish pioneers, and yet he was satisfied that it was necessary to sustain the settlements, in that quarter, in order to prevent the southern progress of European adventurers who were eager to seize the wild and debatable lands lying on both sides of the Rio Grande. Accordingly he proposed to the Spanish court to carry on a war of most inexorable character against the Apaches, Lipans and Mesclaros. He characterized, in his despatches, all the Indian tribes dwelling or wandering between the Presidio of the Bay of Espiritu Santo, in the province of Texas, to beyond Santa Gertrudis del Altar, in Sonora,—the two opposite points of the dangerous frontier line,—as Apaches or their hostile colleagues; and he resolved to fight them, without quarter, truce, or mercy, until they surrendered unconditionally to the power of Spain.