...d approached they were busily engaged shoeing horses. To-day the command of Colonel Duffle passed through Thoroughfare Gap, after a brief fight, and to-night occupies Middleburgh, five miles from Aldie , and in the rear of Stuart's army. Stuart will have to fight to-morrow at a disadvantage, or, what is more probable, sneak off to-night. Captain Allen, of the Fourth New-York cavalry, came throug...