... heavy tramp of men, and the metallic voice of the corporal of the guard relieving his comrades. At 5 o'clock, P. M., we passed a light-ship and hailed her, our object being to discover whether any United States vessels were in the neighborhood waiting to convoy us up the Potomac River. We had heard that the forts at Alexandria were ready to open upon us if we attempted to pass up, and our steamer was of s...