October 29th. The corps did not commence crossing until to-day. At 4 P. M. our division struck tents, and at five o’clock were en route. We crossed the Potomac with rather heavy hearts, and advanced directly up the valley, skirting along the mountain’s base; marched six miles, and then halted, and bivouacked on the north side of Key’s Pass. As soon as the troops were placed in position, I rode back to Harper’s Ferry with General Meagher and an escort, to get my teeth put in order by a dentist, a friend of Captain La Valley, the acting brigade commissary. My teeth lately have been very troublesome, and as we are constantly exposed I thought the present chance too good to be overlooked. I put up with La Valley, who is a bon vivant as well as a good commissary, and enjoyed a pleasant evening with a crowd of friends.