Tuesday, 17th.—Moved off last night about 12 o’clock. Army slowly falling back. Halted at 10 A. M.; some skirmishing on our left. 3 P. M., put under arms at once, and moved back one-half mile and formed in line of battle; heavy firing in our front. We are formed in three lines of battle, across a beautiful valley; we are in third line. Lay down to rest at dark.