n after encountering it, stumbled on Breckenridge's
corps of infantry on the march, apparently heading for Shepherdstown.
The surprise was mutual, for Torbert expected to meet only the
enemy's cavalry, while the Confederate infantry column was
anticipating an unobstructed march to the Potomac. Torbert attacked
with such vigor as at first to double up the head of Breckenridge's
corps and throw it into confusion, but when the Confederates realized
that they were confronted only by cavalry, Early brought up the whole
of the four infantry divisions engaged in his manoeuvre, and in a
sharp attack pushed Torbert rapidly back.

All the advantages which Torbert had gained by surprising the enemy
were nullified by this counter-attack, and he was obliged to withdraw
Wilson's division toward my right, to the neighborhood of Duffield's
Station, Merritt drawing back to the same point by way of the
Shepherdstown ford. Custer's brigade becoming isolated after the
fight while assisting the rear guard, was also obliged to retire,
which it did to Shepherdstown and there halted, picketing the river
to Antietam ford.

When Torbert reported to me the nature of his encounter, and that a
part of Early's infantry was marching to the north, while Fitzhugh
Lee's cavalry had gone toward Martinsburg, I thought that the
Confederate general meditated crossing his cavalry into Maryland, so
I sent Wilson by way of Harper's Ferry to watch his movements from
Boonesboro', and at the same time directed Averell, who had reported
from West Virginia some days before, to take post at Williamsport and
hold the crossing there until he was driven away. I also thought it
possible that Early might cross the Potomac with his whole army, but
the doubts of a movement like this outweighed the probabilities
favoring it. Nevertheless, to meet such a contingency I arranged to
throw my army on his rear should the occasion arise, and deeming my
position at Halltown the most advantageous in which to await
developments, my infantry was retained there.

If General Early had ever intended to cross the Potomac, Torbert's
discovery of his manoeuvre put an end to his scheme of invasion, for
he well knew that and success he might derive from such a course
would depend on his moving with celerity, and keeping me in ignorance
of his march till it should be well under way; so he settled all the
present uncertainties by retiring with all his troops about
Kerneysville to his ol