of killed and wounded was estimated at more than a thousand.
After this action, both parties crossed the river, and Mexico became the theatre of warfare. The Mexican army withdrew at first to Matamoras, at the mouth of the Rio Grande, and afterward to San Luis de Potosi; Arista was deprived of his command, and brought to trial before a council of war.
This was the opening of the conflict, and this might well have been the end, if Mexico had been capable of rational negotiation. But there was no government long enough in place to be negotiated with. The special envoy sent from Washington, agreeably to an intimation on the part of one President, that negotiations would be cordially entered upon, was refused an audience by the new President who had usurped the place of the other one. Such weakness in Mexican high places furnished an excuse to the American government for continuing the war, while this same weakness on the part of their antagonist made it almost discreditable for the United States to continue an aggressive warfare upon forces so unequal.
However, the war was begun. Hostilities had been opened by Mexico, and the American people of all parties were aroused. Bills were promptly passed in Washington providing men, money, and munitions with alacrity, as if there were but one opinion of the justice of the cause. The President was authorized to call for volunteers, in any number not exceeding fifty thousand, to serve for the period of one year, or during the war, and volunteers readily answered the appeal to arms.
