The Civil War: A Narrative: Volume One: Fort Sumter to Perryville by Shelby Foote:
They came soon enough. In fact, they came immediately. Coincident with the return of the messenger, Johnston’s right caved in, the troops there scattering headlong, demoralized and crying like their foes the year before: “We are betrayed!”
Primarily, though, he lost that wing of his army not because of a Federal advance, as he had feared, but because of Zollicoffer’s rashness and military inexperience. After occupying Cumberland Gap, the Tennessean had been ordered to move seventy miles northwest to Mill Springs, on the south bank of the Cumberland River, from which position he could parry an enemy thrust either toward the Gap, where he had posted a guard, or toward Nashville, 150 miles southwest. However, when Crittenden reached Knoxville, assuming command of the region, he learned to his amazement that Zollicoffer had not been content to remain south of the river, but had crossed and set up a camp on the opposite bank. Here at Beech Grove, with a wide unfordable river to his rear, the Tennessean was defying a Union army twice his size and attempting to stir up the doubtfully loyal citizens with proclamations which boldly inquired, “How long will Kentuckians close their eyes to the contemplated ruin of their present structure of society?”
Despite this evidence of literary skill, Crittenden now began to doubt the former editor’s military judgment, and at once dispatched a courier, peremptorily ordering him to recross the river. But when he went forward on inspection in early January, to his even greater dismay he found the citizen-soldier’s army still on the north bank. Zollicoffer blandly explained that Beech Grove afforded a better campsite; he had stayed where he was, in hopes that they could talk it over when Crittenden arrived. Then too, he explained—to the West Pointer’s mounting horror—there were reports that the Yankees were advancing, which made falling back seem a cowardly or at any rate not a manly sort of action.