d. WINFIELD SCOTT."

Worth's division, now preceded by Harney's cavalry, moved from San
Augustin on the main road toward the City of Mexico. These were
followed by the other divisions of the army. On this route was
situated the _pedregal_, which is a field of volcanic rock of very
uneven surface. It is between the roads leading to the capital from
San Augustin and Padierna. A reconnoissance of the _pedregal_ was made
by Lieutenants Robert E. Lee and Pierre G.T. Beauregard, who reported
that there was a passage for wagons of only a mile, and the remainder
might be crossed by infantry, carefully picking the way. The enemy
were in position beyond the _pedregal_ with considerable artillery.

General Scott, on the night of the 18th, ordered a movement in the
direction of Padierna. Worth was ordered to cover San Antonio, Quitman
to hold San Augustin, and Pillow to march over the _pedregal_, while
Twiggs was to cover and support Pillow's movement. On the morning of
this movement the Mexican General Blanco was ordered to construct
batteries, and General Mejia to take position on the Pelon Cuauhtitlan
to command the expected movements of the American army. General Santa
Anna wrote from San Antonio through the Minister of War to General
Valencia, at San Angel: "The general in chief directs me to say to
your Excellency that the enemy having now [August 18th, 3
P.M.] taken up a position on our left in front of San Antonio
with a part of his forces, it is clear that to-morrow at the latest he
will undertake the attack of this fortification, although it appears
there is a movement going on at the same time on our right. His
Excellency therefore directs you at daylight to-morrow morning to fall
back with your forces to Coyoacan, and send forward your artillery to
the fort and the _tete-de-pont_ at Churubusco."

General Valencia declined to obey this order, giving his reason as
follows: "I should like much to be able to obey this order, but, in
view of present circumstances, my conscience as a military man and my
patriotism will not permit me. I believe the national cause will be
lost if I should abandon these positions and the road leading from San
Augustin through Padierna to these points. To me it is as clear as
the light of day that the enemy will undertake his attack, if not
to-morrow, the day after, and that he desires to make two attacks at
the same time, the one true and the other fa