was his purpose to retreat on Tlascala, and in that
capital to decide according to circumstances on his future operations.
After some discussion, they agreed on the causeway of Tlacopan as the
avenue by which to leave the city. It would, indeed, take them back by a
circuitous route, considerably longer than either of those by which
they had approached the capital. But, for that reason, it would be less
likely to be guarded, as least suspected; and the causeway itself, being
shorter than either of the other entrances, would sooner place the army
in comparative security on the mainland.

There was some difference of opinion in respect to the hour of
departure. The daytime, it was argued by some, would be preferable,
since it would enable them to see the nature and extent of their danger,
and to provide against it. Darkness would be much more likely to
embarrass their own movements than those of the enemy, who were familiar
with the ground. A thousand impediments would occur in the night, which
might prevent them acting in concert, or obeying, or even ascertaining,
the orders of the commander. But, on the other hand, it was urged that
the night presented many obvious advantages in dealing with a foe who
rarely carried his hostilities beyond the day. The late active
operations of the Spaniards had thrown the Mexicans off their guard, and
it was improbable they would anticipate so speedy a departure of their
enemies. With celerity and caution, they might succeed, therefore, in
making their escape from the town, possibly over the causeway, before
their retreat should be discovered; and, could they once get beyond that
pass of peril, they felt little apprehension for the rest.

The general had already superintended the construction of a portable
bridge to be laid over the open canals in the causeway. This was given
in charge to an officer named Magarino, with forty soldiers under his
orders, all pledged to defend the bridge to the last extremity. The
bridge was to be taken up when the entire army had crossed one of the
breaches, and transported to the next. There were three of these
openings in the causeway, and most fortunate would it have been for the
expedition, if the foresight of the commander had provided the same
number of bridges. But the labor would have been great, and the time was
short.

At midnight the troops were under arms, in readiness for the march. Mass
was performed by Father Olmedo, who invoked the protec