When our advanced corps encamped near the banks of the stream on the 19th, an armed _reconnoisance_ was sent forward to examine the country. On reaching the river, our scouts discovered that the opposite side was lined with a body of _ranchero_ cavalry, from whom they learned, although no opposition was made to our examination of the ford, that we should be treated as enemies if we attempted to pass it. Impossible as it was to ascertain accurately the amount of the opposing force, our men were prepared for the worst, and, at an early hour of the 20th, the cavalry and first brigade of infantry were thrown in position, at the ford, while the batteries of field artillery were formed so as to sweep the opposite bank. All was now anxiety and eagerness among our gallant men. Far along the borders of the river, above and below, the bugles of the enemy were heard ringing out in the clear morning air. But the hope of frightening our men by overwhelming numbers was of no avail. Our pioneers worked steadily on the road they were cutting to the brink of the river; and, when all was ready for the passage, the adjutant general of the Mexican forces appeared on the ground for a final effort of intimidation. With Spanish courtesy, he informed our general that positive orders were given to his men to fire upon our forces if they attempted to cross, and that our passage of the river would be considered a declaration of war. At the same time he placed in Taylor's hands a warlike proclamation issued by Mejia at Matamoros on the 18th, containing unequivocal manifestations of the intention of the Mexicans to molest us. Our commander-in-chief, however, was not to be deterred by these threats from the fulfilment of the orders he had received to pass the Rio Grande. He answered the officer that he would "_immediately_ cross the river, and that if his hostile party showed itself on the other bank after our passage was commenced, it would unquestionably receive the fire of our artillery." In the meantime the second brigade, which had encamped some miles in our rear, came up and formed on the extreme right; and, as the road to the river bank was by this time completed, the order to advance was given.