Monterey, an old city, the capital of the State of Nuevo Leon, contained about forty thousand inhabitants. It is situated on the left bank of the San Juan, a small stream that empties into a larger one of the same name.
It had three forts. The main one, called the Black Fort, was out on the plain north of the city. Fort Tanaria was in the suburbs, in the northeast part of the city; and about two hundred yards distant south of it was a third fort, the guns of which commanded the interior of the Tanaria. The hill on the slope of which was the bishop's palace was also fortified; and strong earthworks surrounded the city on the north and east sides, with isolated works to the south and west.
Gen. Ampudia was in command, with a force of seven thousand regular troops, and a large volunteer force. A reconnoissance of the place by the engineer officers, having been completed, dispositions to capture the city were made by detaching Gen. Worth, with his division, and Col. Hays, with his Texas regiment, to gain the road to Saltillo, by storming its defenses, and thereby cutting off the supplies of the enemy and holding his line of retreat. To accomplish this part of Gen. Taylor's plan, Worth started late on the 20th, and on the 21st made the attack, and was successful in carrying the detached works and securing the road to Saltillo. By way of _divertisement_, or at most a diversion in favor of Worth, Gen. Taylor moved Garland's division of regulars and a division of volunteers, some cavalry, and our battery, down to the northeast part of the city. As is often the case, this demonstration terminated in a fight, and the capture of the fort or redoubt called Tanaria and buildings adjacent. Our battery penetrated by a street some distance into the city. The houses were mainly built of soft stone or adobe, and the shot from the batteries in the town passed through the buildings, covering the men, horses, and guns with lime and dust, blinding us so that we could see nothing. From this situation we were ordered out. In passing an opening in the works a shot killed the two wheel horses to one of the caissons, and Lieut. Reynolds and I with the men threw, or pushed, the horses and harness into the ditches on either side, and after we had done this and gone some distance, another shot passed through two horses of one of the guns. These horses were loosed, and with their entrails dragging, in agony of pain, I suppose, commenced eating the grass.