Green, he obstructed the tunnel seven miles north of Gallatin, and burned an additional number of wooden superstructures. It was learned about the same time that Forrest had again reached the Cumberland with several thousand cavalry, and was moving toward Nashville. Buell at once sent a cavalry force of seven hundred under Brigadier-General Johnson, an old regular-cavalry man, after Morgan. Johnson overtook him near Gallatin, but, owing to the misbehavior of part of his command, was beaten, and he himself taken prisoner with one hundred and fifty men. The remainder of his men refused to surrender and got away. Johnson was afterward charged with incapacity and cowardice in this affair.
This bad news produced no little anxiety in the army and at our division headquarters. The interruption of rail communication with Louisville, our primary base, was, indeed, a most serious blow, and, if long continued, was bound to frustrate the plan of campaign and compel retro grade movements. General Nelson was therefore detached from his division and ordered to Kentucky to restore our communications and clear that State of Morgan and the guerrillas. The army commander also telegraphed to General Grant, by authority of General Halleck, who had in the meantime been called to Washington as general-in-chief of all troops in the field, for two additional divisions, one to be used for protecting the line north of Nashville, and the other for service on the front in the general advance, which was still believed possible notwithstanding the threatening occurrences in the rear.
To General McCook's command now fell the part of an active corps of observation. On August 19 it received orders, upon the first intelligence of an advance of the enemy along the Sequatchie, to move promptly up that valley to check him and observe his movements. If pressed, he was to fall back over the so-called Therman road, diverging from the Sequatchie to the north, upon the main Union force that was expected to advance from McMinn-
