the foot of the mountains, he discovered a body of the enemy's lancers posted about a mile in his front, near the hacienda of Buena Vista. Promptly ordering a charge, the Mexicans were compelled to make a hasty retreat. General Twiggs reached Ayotla, fifteen miles from Mexico, on the 11th of August, where he halted with his division. The other divisions of the army soon came up, and encamped in his rear, about the head of Lake Chalco.
There were three different routes that suggested themselves to General Scott, by which the city could be approached; the first, to make the circuit of Lake Tezcuco, and enter it by way of Guadalupe, from the north; the second, to proceed straight forward upon the National Road; and the third, to turn Lakes Chalco and Xochimilco, and approach it on the south. The first was ascertained to be too tedious and too circuitous to be undertaken. Close and daring reconnaissances of El Peñon were made on the 12th and 13th, which disclosed the strength of the position, and convinced the American commander that the work could not be carried except at a great sacrifice of life. Several skirmishes took place with the enemy's advanced corps, while these reconnaissances were being made, and on the 13th a superior force of Mexican cavalry were attacked and routed by a small party of dragoons escorting Lieutenant Hamilton, aid-de-camp to General Scott, who was ordered to make an examination of a foundry near Mil Flores, a small town five or six miles beyond Chalco. On the 13th instant, another reconnaissance was directed upon Mexicalcingo, when it was found that, masking El Peñon, the passage of the bridge at that place could be forced. But it was also ascertained that the causeway beyond the bridge
