IF YOU SUFFERED through "The Blue and the Gray" last November and are in need of a reminder that the Civil War was not a soap opera, Stephen Sears provides it in Landscape Turned Red.

Sears' subject is the battle of Antietam, or Sharpsburg if your ancestors marched with Lee, Jackson and Longstreet.

No other Civil War battle captures so much of the essence of that terrible, long-ago war; and no other book so vividly depicts that battle, the campaign that preceded it and the dramatic political events that followed.

September 17, 1862, was the bloodiest, most deadly day of the bloodiest, most deadly war this nation has ever fought. Between sunrise and sunset 23,000 Americans fell in combat. By comparison, on D-Day, casualties for all Allied forces totaled 10,000.

The battle and the war should have ended on September 16. Lee was outnumbered four to one. But his opponent, the ever-cautious George B. McClellan, did not move. When his attack finally began at sunrise on the 17th, the odds had shortened to three to one. The Confederate lines sagged, disintegrated, reformed, and held for seven hours.

Then at 1 o'clock Lee's right, where 400 Rebels were holding a bridge against 12,000 under General Ambrose E. Burnside, gave way. By 4 o'clock the end of the battle and the war was again in sight. Burnside's regiments were pouring into Lee's right and rear. His one avenue of escape across the Potomac would soon be cut, and Lee could choose between surrender or annihilation.

It was not to be. General A.P. Hill had left Harpers Ferry at 7:30 that morning with the last division in Lee's army and marched the 17 tortuous miles to Sharpsburg at a killing pace. He arrived just in time to fall upon the exposed left flank of the Union assault. Jubilation turned to panic as the Union divisions fled back toward the creek they had so recently crossed. Lee's lines were restored one last time. The battle was over.

Few battles have been more politically significant. Failure to win a decisive victory at Sharpsburg helped to end the military career of McClellan, one of the more likely candidates for "man on horseback" in American history. By forcing Lee to abandon his invasion of the North, the battle destroyed the best chance for European recognition of the Confederacy. And it gave Lincoln the excuse he needed to issue a document he had been carrying about in his coat pocket since July--the Emancipation Proclamation.

Sears takes his title from Private David Thompson of the 9th New York. As he sprang to his feet to begin the attack that opened the final stage of the battle--a charge straight into the face of massed artillery-- Thompson remembers that it seemed as though "the whole landscape for an instant turned slightly red." In other parts of that field, the land had turned literally and horribly red. From a sunken road about a mile north--known from that day forward as Bloody Lane-- to D.R. Miller's cornfield, less than a mile farther, 18,500 men were dead, wounded or missing, one-third of the nearly 60,000 who fought there.

But it is not the statistics that make Sears' narrative so gripping. Years of combing letters, diaries and early accounts by the men who fought along the banks of Antietam Creek have provided moving vignettes of every stage of the battle.

When the first Union charge sweeps through the cornfield and collides with Confederate defenses, a brigade from Pennsylvania and New York and a brigade of Georgians stand in two lines, 250 yards apart, and shoot each other to bloody shambles in a continuous roar of musketry.

An hour later, a regiment of Boston's elite strikes a unit recruited from "among the denizens of the New Orleans waterfront." When the action is over, two-thirds of both are casualties.

At almost an the same moment, a green Pennsylvania regiment marches into battle past a mangled artilleryman, screaming for someone to shoot him.

Later, just behind Bloody Lane, Colonel John B. Gordon, wounded five times, falls unconscious, his face in his bullet-torn cap; the bullet hole saves him from smothering in his own blood.

There were moments of gallantry as well as horror: in the early hours of battle, batteries fall silent on both sides as a Confederate cavalryman rides out to lead a hysterical group of women and children from a farmhouse sitting squarely between the lines.

There is even humor: a Pennsylvania regiment, moving toward Bloody Lane, is temporarily routed when a Rebel shell overturns farmer Roulette's beehives.

Occasionally there is both gallantry and humor: a Confederate infantryman attacking up the Hagerstown Pike pauses in response to the cries of Union wounded and tosses them his canteen. Fifteen minutes later he is back: "Hurry up there! Hand me my canteen! I am on the double-quick now myself." Someone tosses him the canteen, and he is gone.

As compelling as the scenes of battle is Sears' analysis of strategy, tactics and personalities. He probes the thinking and examines the behavior of commanders-- particularly of the ill-led Army of the Potomac--in the style of Lee's Lieutenants, the classic study of Civil War command by Douglas Southall Freeman.

As there is only one other modern book that focuses exclusively on this battle, The Gleam of Bayonets: The Battle of Antietam and the Maryland Campaign of 1862 (1965) by James Murfin, a comparison is obligatory. It is no insult to Murfin's outstanding work to say that Landscape Turned Red is at least marginally better in almost every respect, the principal exception being Murfin's superb analysis of McClellan and his relationships with superiors and subordinates.

Sears, a former editor at American Heritage and colleague of Bruce Catton, is more adept at keeping the reader fixed in time and place, no mean feat when you consider that Lee's generals included an A.P. Hill and a D.H. Hill, as well as a J.R. Jones and a D.R. Jones-- plus three brigadiers named Anderson. Not to mention four cornfields, three orchards and three bridges that figured prominently in the battle.

The maps in Landscape Turned Red are less cluttered and easier to read because Sears uses larger units--brigades rather than regiments. He also maps the campaign leading up to the battle, the one serious lack in Murfin's book. Although Sears had access to material not available to Murfin, including the extensive collection of letters by Antietam veterans at Dartmouth College, he seems to have found nothing that would shed new light on the major actions and decisions by the battle's commanders.

His chief disagreement with Murfin, and indeed with everyone who has written on Antietam for the last three decades, is his interpretation of one of the most intriguing episodes of the war--the famous Lost Order.

Lee began his invasion of Maryland on September 4, following his victory at the second battle of Manassas. Crossing the Potomac near Leesburg, he marched north to Frederick. There on September 8, he issued Special Orders No. 191--initiating a daring gamble whose object was the seizure of Harpers Ferry, a Union supply depot garrisoned by 10,000 men. Lee badly needed the military stores there; and if he was to march his army to Harrisburg as he planned, a supply line back to the Shenandoah valley had to be cleared.

Lee divided his nine divisions into four commands. Three, composed of six divisions, were sent by widely diverging routes to encircle Harpers Ferry. The three remaining divisions, with Lee, were to move across South Mountain to Boonsboro. As the order was being written, McClellan was advancing on Frederick with a force of 85,000 men, twice the size of the Army of Northern Virginia. Lee was counting on McClellan's well-deserved reputation for caution. And it might have been a good bet, except for the Lost Order.

On September 13, two of McClellan's soldiers found a copy of Special Orders No. 191. Sears cannot help us with the question of who lost it. Like other historians, he can only note that it was one of two copies addressed to General D.H. Hill, and enumerate the arguments and theories advanced over the years.

What he does do is provide a new and well-reasoned explanation of Lee's subsequent behavior.

When McClellan was handed Lee's order, a Maryland civilian, sypathetic to the South, happened to be present. He witnessed the Union commander's elation and the immediate burst of activity in the Union camp. This Marylander, whose name has been lost to history, made his way through Union lines to tell General J.E.B. Stuart, who immediately passed the report to Lee.

Conventional wisdom has it that Lee was informed, late on the night of the 13th, that McClellan had his order and knew of his dangerously divided army. Sears argues that Lee learned only that McClellan was suddenly on the move and that Lee did not know his plans had fallen into enemy hands until months later when the story appeared in Northern newspapers.

For unabashed admirers of Lee, including this writer, there is an inherent bias toward Sears' version. It explains the one lapse in Lee's generalship during the campaign--a wait of six to eight hours before shifting his forces to meet the new threat from McClellan.

The case for the conventional wisdom rests primarily on a letter from Lee to Hill after the war, which contains the comment that Stuart was told that McCLellan "was in possession of the order." Sears argues that in this letter, which was intended as a strong rebuttal to an entirely different point, Lee "unintentionally let the knowledge of events gained by hindsight cloud his memory of the exact contents of Stuart's dispatch." He also offers an unequivocal statement by Colonel Charles Marshall, Lee's wartime aide: "I remember perfectly that . . . Gen. Lee frequently expressed his inability to understand the sudden change in McClellan's tactics."

Thus Sears has provided us with both a powerful and a moving book on a interesting subject and a new topic for Civil War scholars and buffs to debate for at least the next century.

In conclusion, a suggestion. After you read this book, make the hour-and-fifteen-minute drive--north to Freedrick, across the mountains to Boonsboro, and down to the valley of Antietam Creek.

Leave early so you can arrive with the sun; you are likely to find the fields and woodlots shrouded in mist, as they were on that morning 120 years past. Most years, you will see corn standing green and tall again in Mr. Miller's field, and a scattering of monuments and markers glowing dimly through the early light--understated reminders of a day and events that defy adequate commemoration.

Come on a weekday, and you can walk the battlelines in solitude. Stop along the way and read again the accounts of courage, pride, foolhardiness, suffering and death. It is a place for thinking on things grand and awful and for placing lesser matters in proper perspective.

Oh yes. I have a more than academic interest in this battle. Eight family members, from both my mother's and father's side, fought in the cornfield or in Bloody Lane. Miraculously all emerged unscathed, but they were not so fortunate on other fields. Of 10 Powell and Williamson brothers who came from south Georgia to fight in Lee's army, three were killed, four wounded, and one permanently disabled by illness.