.... Elzey, or the government, to put in movement nearly 20,000 men! But something else may be behind this demonstration; it may be the purpose of the enemy to strike in another direction, perhaps at Hanover Junction -where, fortunately, we have nearly a division awaiting them. The Hon. Mr. Dargan's letter, received at the department a few days ago, saying that the reinstatement of Gen. Pemberton in command w...