Grant's visit had plainly shown him that the great problem with us was the clothing and subsistence of the troops, and that our very existence depended on it. He therefore determined to ride over the mountains by way of Cumberland Gap, and form his own judgment as to the truth of the reports of the impassable condition of the roads. The weather had hardly moderated at all when he left us on the 4th of January, and this long and severe journey was proof of his forgetfulness of personal comfort in his devotion to duty. Before following him further in his investigation, it may be profitable to go back and note some of the circumstances which brought him to Knoxville. When Longstreet raised the siege of Knoxville, he took position near Rogersville, where he would be in reach of the unbroken part of the railway connecting him with Virginia, which now became his base. His force continued unchanged, and was not materially increased or diminished until the winter was nearly over, when the cavalry which belonged to the Army of Tennessee was ordered back into Georgia. Like Foster, he was reduced to inaction for lack of clothing and supplies. Forage had become very scarce in every part of Tennessee, and it was with great difficulty that the horses were kept alive in either army. [Footnote: Official Records, vol. xxxi. pt. iii. pp. 817, 819.] To go into cantonments, sheltering the men as well as possible, to send all extra horses to the rear and wait for the springing of the grass and the settling of the roads when winter should be over, was the dictate of common-sense, as was clearly seen by everybody on the ground. It was not pleasant to leave the loyal men of the upper counties of the valley to suffer under the Confederate occupation; but nothing short of a continuous and reliable line of supplies would enable Foster to occupy the country up to the Virginia line. There was no gate to be shut behind Longstreet if he were driven out. He could come back as soon as our troops withdrew. Marching and countermarching would destroy the nearly naked and barefoot troops without accomplishing any permanent good.