As he rode back to headquarters at the end of the Battle of Fredericksburg in December 1862, Thomas "Stonewall" Jackson suddenly said, "How horrible is war." Hunter McGuire, his medical officer, agreed: "Horrible, yes. But we have been invaded. What can we do?" "Kill them, sir," Jackson replied. "Kill every man."

Before the start of the Civil War, Jackson, a professor at Virginia Military Institute, wasn't much good at anything. By 1862, he was idolized in the South "for chawing up Yankees by the thousands" — and feared in the North as a religious fanatic and a remorseless killer. When he died from wounds received at the Battle of Chancellorsville, men in blue and gray uniforms agreed that Stonewall Jackson may well have been the best soldier of them all.

In "Rebel Yell," journalist S.C. Gwynne, the author of "Empire of the Summer Moon," captures Jackson's complex character and military genius. And his striking and suspenseful narrative reminds us of the bloody brutality of the Civil War.

Gwynne's Jackson is terribly earnest, secretive, socially awkward and yet "with a simplicity and purity about him — almost a sweetness." He acquired his first slave, Gwynne indicates, and rented him out as a waiter so that the man could buy his freedom. Jackson conceived, organized and financed a Colored Sabbath School, in which he taught slaves to read. And he opposed secession.

According to Gwynne, Jackson fought to repel the invaders of his homeland. As an officer, as Robert E. Lee's "iron fist," however, "there was something lethal about this Confederate general, something grim and unyielding and inexplicable and alarmingly single-minded." As much or more than Ulysses S. Grant, he was an advocate of "total war," who pressed Confederate President Jefferson Davis and Gen. Lee to lay waste to the armies, industries and cities of the North, to make its people "understand what it will cost them to hold the South in the Union at the bayonet's point."

Jackson did not get his wish. Even so, Gwynne paints a graphic picture of what war had come to: footsore armies, forced to march "through hip-deep, ice-encrusted mud into camps that were nothing more than fetid pools of muck"; a desperate world of "death and dismemberment and terrible sickness that killed you as surely as bullets," and "no stasis, no easy living, no resting on laurels, no rest at all, in fact."

We must not forget, of course, that by ending slavery, the Civil War helped our nation atone for its original sin. That said, it's worth remembering, is it not, that all wars, even those fought for righteous causes, take a terrible toll?

Glenn C. Altschuler is the Thomas and Dorothy Litwin professor of American studies at Cornell University.