On 12 April 1864 a Confederate cavalry force, led by General Nathan Bedford Forrest, assaulted and captured an incompetently defended Union fortification in western Tennessee, near Memphis. The unusual number of predominantly African-American troops who were killed during the subsequent rout led the Northern public to charge that a racist massacre had occurred.

Although Lincoln's cabinet decided against systematic reprisals, outraged Federal soldiers took vengeance during several small engagements, foraging expeditions, and anti-guerrilla campaigns. For its part, the Confederacy defended the killings as the result of circumstances ("stubborn resistance") or military necessity, the product of an "unavoidable heat of battle" or "drunken" Blacks who forced the victorious troops to defend themselves. Blacks under arms were not recognized by the Confederacy as soldiers - they were simply runaways, not enemy combatants.

As a former slave trader, General Forrest claimed he would never deliberately have destroyed valuable recaptured property.

Richard Fuchs is the first modern author of a book-length examination of the battle of Fort Pillow. Fuchs seeks to understand the event as a product of the social milieu and individual personality of General Forrest. For Fuchs, Forrest was an accessorial inspiration before and a passive participant during the massacre. Forrest encouraged his troops' desire for vengeance against African-Americans under arms and against western Tennessee Unionists who had, in many cases, deserted the Confederate armies.

He allowed the wanton killings, some of which continued into the next day, and only belatedly joined the efforts of some subordinates to end the massacre.

While there is no evidence that Forrest personally took part, An Unerring Fire reminds the reader that it would have been utterly unlike him to yield to his men's behavior and prejudices if he did not share them nor fail to intervene forcibly where and when he opposed them. "The Devil," as Sherman called Forrest, singled out Fort Pillow to dispel the notion of Blacks as soldiers and to avenge recent Tennessee Loyalist maraudings.

Fuchs meticulously narrates minute details of the battle and the massacre, compiling corroborating dispatches and eyewitness testimony of soldiers on both sides, examining these sources critically, and systematically debunking each of the Confederate rationalizations and convincingly describing Forrest's involvement in the massacre. He is both detective and lawyer at work, and his conclusion reads like a prosecutor's summation to the jury.