Gerald Early is the Merle King professor of modern letters at Washington University in St. Louis.

How “untold” is Linda Hervieux’s story of black soldiers on D-Day? Military historian Gerald Astor does not mention the all-black 320th Barrage Balloon Battalion, which was part of the initial invasion force on Omaha Beach, in “The Right to Fight,” his study of African Americans in the military. (In fact, in his book “June 6, 1944: The Voices of D-Day,” Astor writes, “The backgrounds of those who happened to be there and what befell them before, during, and after June 6, 1944, are a mosaic portrait of white American men — African-Americans were almost entirely excluded from combat roles until late in the war.”) Neither does Bernard C. Nalty mention the 320th in his book about black Americans and the military, “Strength for the Fight.” Nor does Gail Buckley in her “American Patriots.” One of the few historians who do mention the 320th is Stephen E. Ambrose, who observes in his book on the Normandy invasion, “D-Day,” that the unit “was a unique outfit . . . that brought in barrage balloons on LSTs [Landing Ship, Tank] and LCIs [Landing Craft, Infantry] in the third wave and set them up on the beach, to prevent Luftwaffe strafing.”

According to Hervieux in “Forgotten,” her book-length study of the 320th, the unit “drew substantial praise that summer from visiting newspapermen fascinated with their mission.” (Barrage balloons, also called blimps, were controlled on the ground by small teams; their purpose was to prevent enemy aircraft from flying low enough to hit their targets with accuracy.) So it cannot be said that the unit was neglected in contemporaneous accounts of D-Day.

Indeed, although the military was racially segregated at the time (in part to please white Southerners who were over-represented in that institution, in part because most whites did not consider blacks emotionally capable of combat or intellectually capable of leadership), many liberals in Roosevelt’s New Deal government thought it was important that black soldiers be praised as much as possible to reassure the black public that they, too, had a stake in this war. In 1944, the Army released “The Negro Soldier,” a well-made propaganda film providing a glowing historical account of blacks and the American military. In 1945 came the release of “Wings for This Man,” a propaganda film about the Tuskegee Airmen.

The difficulty for the United States during World War II was figuring out how to keep the Army from being torn apart by racial strife while maintaining white supremacy in its ranks; in other words, how to weave black Americans into the defense fabric of the nation while keeping them distinct as a socially inferior group. Nothing symbolizes this contradiction more than the fact that black troops made up less than 1 percent of the initial combat invasion force on Omaha Beach on D-Day — just the 621 men of the 320th — yet the commanders were loath to have any black soldiers at all present at the launch of this important stage of the war. After all, there were plenty of white barrage balloonists to send to the beaches that day. The nature of the job meant that the black balloonists could be part of the grand picture of the invasion, but separated from everyone else and ordered not so much to fight as to keep the balloons afloat so they could do their job of preventing enemy aerial attacks.

‘Forgotten: The Untold Story of D-Day's Black Heroes, at Home and at War’ by Linda Hervieux (Harper)

This tension is captured well in “Forgotten.” And while Hervieux does a good job providing a close-up view of some of the men who made up the unit (she interviewed 12 survivors), most of the book is about African Americans and the U.S. military generally before and during World War II, of which there are many accounts. Her D-Day invasion story is compelling, but there are loads of D-Day narratives. What is fresh here is the intimate and detailed accounts of the young lives of several of the men of the 320th, including quotes from letters home. The chapter devoted to describing the history of warfare ballooning and the development of barrage ballooning will also be informative to most readers. The book, on the whole, reads well, even vividly, but the doubting Thomases who told Hervieux that she did not have enough material directly related to her subject to make a book were right.

I wonder if the 320th has been lost to histories of D-Day because its members were barrage balloonists — an underappreciated combat role in many modern military histories — rather than because they were black. As Hervieux herself notes, Cornelius Ryan’s “The Longest Day,” by far the most influential and popular book about the invasion, said that only two German planes halfheartedly attempted to strafe American forces that morning (deftly dramatized in the film version of Ryan’s book), and the Luftwaffe was, by this stage in the war, a mere shell of dead pilots, empty petrol cans and Goering’s bluster. Perhaps the barrage balloonists, regardless of their race, seemed less important in the popular imagination than other combat forces. By the time of the D-Day invasion, the Allied forces, for the most part, controlled the skies.

In any case, Hervieux’s reclamation act is a welcome addition to our understanding of the war and the American military.

The Untold Story ofD-Day’s Black Heroes, at Home and at War

By Linda Hervieux

Harper. 353 pp. $27.99