the south and west, the company of sappers and miners was transferred to General Worth
's division, which now took the lead, and the company moved at its head to San Augustin
, occasionally repairing the roads as far as was practicable.
As soon as General Santa Anna
learned this movement of the American
forces, he withdrew the greater portion of his troops, with several pieces of artillery, from El Peñon and Mexicalcingo, where he had been expecting the first shock of battle, and, establishing his Headquarters at the hacienda (hamlet) of San Antonio
, began to labor upon the lines of defence in that vicinity.
On the morning of the 18th, General Worth
's division was moved forward a couple of miles on the causeway leading from San Augustin
to San Antonio
, and took up its position in front of the latter place, the men encamping on both sides of the road.
Here a careful reconnoissance was made of the defences of San Antonio
, in which Lieutenant McClellan
His company was then transferred to General Twiggs
's division, and moved at its head, across the Pedregal, to Contreras
During the first day of the battle of Contreras
(August 19), Lieutenant McClellan
, while reconnoitring, ran into a Mexican regiment, and had his horse shot under him by a musket-ball.
On the same day, while posting Magruder
's battery, he had another horse killed under him by a round shot.
Still later, while in temporary command of a section of the same battery whose officer had been mortally wounded, he was knocked down