Loring's brigades reached him from the Staunton and Parkersburg line early in December. Loring did not arrive in person until very nearly the end of the month of December, but Jackson, with characteristic energy, improved the opportunity to drill his command and equip it for service, and to organize certain cavalry companies in his district into a regiment, under the command of Lieut.-Col. Turner Ashby.
Unwilling to be idle and leave his foe to believe that he was not ready for action, Jackson dispatched a small force of infantry and a battery to break Dam No. 5, seven miles above Williamsport, across the Potomac, which supplied a long level of the canal with water, and thus destroy the line of communication between Cumberland and Washington. On the afternoon of December 6th, Jackson's force reached the dam, and while he kept up an active skirmish across the Potomac for two "days, an effort was made to break the dam on the night of the 7th, but with little success. Unwilling to be foiled in his under-taking, Jackson again left Winchester on the 16th with a larger force, and on the 17th, having disposed his troops to provide against a flank movement and also to make demonstrations at Dam No. 4, at Williamsport, he sent parties to break Dam No. 5 at its Virginia end. The Federal infantry and artillery kept up a vigorous and annoying fire from the Maryland side on Jackson's working party, so that little was accomplished during the day; but that night Captain Holliday, of the Thirty-third, and Captain Robinson, of the Twenty-seventh, volunteered to go down with their companies and wade in and cut out the cribs that supported the dam. It required heroic endurance to stand waist deep in the water on a cold December night, and under a constant fire of the enemy, but a partial breach was made and the cribs so loosened that a later freshet made a wide gap in the dam and rendered useless for some time a long stretch of the canal. During Jackson's stay to effect the object of this expedition, it became evident from the arrival of Federal regiments to reinforce the command at Williamsport, that it would be hazardous for him to cross the Potomac and attack his opponents, so he withdrew on the 21st and returned to Winchester.
While engaged in the expedition to Dam No. 5, news reached Jackson of the decisive victory Gen. Edward
