al Taylor in the earlier engagements of the Mexican war."* (*
Grant's Memoirs volume 1 page 168.) These troops were all regulars,
and they were those who carried Scott in triumph from the shores of
the Gulf to the palace of Santa Anna. The volunteers had proved
themselves exceedingly liable to panic. Their superior intelligence
had not enabled them to master the instincts of human nature, and,
although they had behaved well in camp and on the march, in battle
their discipline had fallen to pieces.* (* Ripley's History of the
Mexican War volume 2 page 73 etc.) It could hardly be otherwise. Men
without ingrained habits of obedience, who have not been trained to
subordinate their will to another's, cannot be expected to render
implicit obedience in moments of danger and excitement; nor can they
be expected, under such circumstances, to follow officers in whom
they can have but little confidence. The ideal of battle is a
combined effort, directed by a trained leader. Unless troops are
thoroughly well disciplined such effort is impossible; the leaders
are ignored, and the spasmodic action of the individual is
substituted for the concentrated pressure of the mass. The cavalry
which dissolves into a mob before it strikes the enemy but seldom
attains success; and infantry out of hand is hardly more effective.
In the Mexican campaign the volunteers, although on many occasions
they behaved with admirable courage, continually broke loose from
control under the fire of the enemy. As individuals they fought well;
as organised bodies, capable of manoeuvring under fire and of
combined effort, they proved to be comparatively worthless.

So Jackson, observant as he was, gained on Mexican battle-fields some
knowledge of the shortcomings inherent in half-trained troops. And
this was not all. The expedition had demanded the services of nearly
every officer in the army of the United States, and in the toils of
the march, in the close companionship of the camp, in the excitement
of battle, the shrewder spirits probed the characters of their
comrades to the quick. In the history of the Civil War there are few
things more remarkable than the use which was made of the knowledge
thus acquired. The clue to many an enterprise, daring even to
foolhardiness, is to be found in this. A leader so intimately
acquainted with the character of his opponent as to be able to
predict with certainty what he will do under any given circumstances
may set aside