critical, for the ammunition began to run low, and it was realized
that, if the Mexicans discovered this, they would sweep down and
cut their defenseless opponents to pieces. Face to face with this
predicament, the Colonel on September 23rd, called for a volunteer
to carry a dispatch to Headquarters, and Grant instantly responded.

To reach his destination it was necessary to run the gantlet of the
enemy, for every opening from the Plaza was completely exposed to
their fire. But trusting in the fleetness of his horse, the young
lieutenant leaped into the saddle and, swinging himself down, Indian
fashion, on one side of his steed so as to shield himself behind
its body, he dashed away on his perilous mission. A roar of muskets
greeted him at every corner, but he flashed safely by, leaping
a high wall which lay across his path and then, speeding straight
for the east end of the town, reached the commanding General and
reported the peril of his friends.

Meanwhile the Americans began one of the most curious advances
ever made by an army, for General Worth, finding that he could not
force his troops through the streets leading to the Plaza without
great loss of life, ordered them to enter the houses and break down
the intervening walls, so that they could pass from one adjoining
house to another under cover, directly to the heart of the city.
This tunneling maneuver was executed with great skill, and when
the walls of the houses nearest the Plaza were reached and masses
of men stood ready to pour through the openings into the Square,
its astonished defenders gave up the fight and promptly surrendered
the city.