miles from the Rio Sacramento, a branch of the Rio Conjos, one of the tributaries of the Rio Grande, the country begins to slope gently down to that stream. The position occupied by the Mexicans was upon an elevated plain, in the centre of a peninsula formed by the Arroyo Secó and Arroyo Sacramento, the two principal branches of the Rio Sacramento, which have their rise in the mountains on the right of the valley, at this point nearly four miles wide, and cross it in an easterly direction nearly parallel to each other. The Arroyo Secó, on the north, inclines to the south when it reaches the eastern range of mountains, and, uniting with the Arroyo Sacramento, they together form the main river. The road to Chihuahua crosses this peninsula from north to south; on its left the plain rises abruptly in a bench, fifty feet high, sloping upwards from every side towards the north-east corner, where it culminates in a rocky knoll called the Cerro Frigolis, one hundred and fifty feet above the plain; but on the right it is smooth and unbroken, descending gradually from the hilly bench, along the base of which the road passes. On the southern bank of the Arroyo Sacramento there is a range of sierras, separated by deep gullies, and forming right angles with the course of the stream. The easternmost ridge is the Cerro Sacramento, which rises on the right of the road, just in rear of the rancho Sacramento. Below the Cerro Sacramento on the east is the valley of the Rio Sacramento, about one mile wide, through which winds the road to Chihuahua.
Upon the Cerro Frigolis, was a redoubt and battery, with a stone wall, and abattis in its rear, extending across the bed of the Arroyo Secó to the mountains on the opposite bank. Seven hundred yards west of the Cerro Frigolis there was another redoubt. There was a re-
