He had not heard the call for a halt.
General Franklin Pierce had joined the army in Mexico, at Puebla, a short time before the advance upon the capital commenced.

He had consequently not been in any of the engagements of the war up to the battle of Contreras.

By an unfortunate fall of his horse on the afternoon of the 19th he was painfully injured.

The next day, when his brigade, with the other troops engaged on the same field, was ordered against the flank and rear of the enemy guarding the different points of the road from San Augustin Tlalpam to the city, General Pierce attempted to accompany them.

He was not sufficiently recovered to do so, and fainted.