Nations tend to write their histories by forgetting the shameful parts. In America, once-buried issues associated with slavery and the genocide against Native Americans have resurfaced and been incorporated into the national memory. But World War II has thus far been held apart as an era that is almost beyond reproach. Indeed, the people who led the country in the 40’s and fought the war have been transformed from mere mortals — with faults like the rest of us — into sudden secular saints. They were dubbed “the greatest generation” and made out to be peerless in bravery and moral rectitude.

But when it comes to racial justice, any claim of moral superiority is false on its face. Franklin Roosevelt and the national political leadership failed when tested on the great moral issue of the 20th century. It was within Roosevelt’s power to strike Jim Crow segregation from the military — which is precisely what Harry Truman would do three years after the war ended. Roosevelt, however, embraced apartheid segregation, actually spreading it from the Army, where it had been long established, into other major branches of the military.

Historians now agree that in the process, the military transplanted Jim Crow racism from the South into parts of the country where it had not previously existed. It further legitimized retrograde racial attitudes by enforcing apartheid policies in the towns where troops spent leisure time.

Beyond that, providing racially segregated living and training arrangements — as well as separate command structures — taxed the country’s resources and created a logjam among black recruits. With too few segregated outfits to hold them, hundreds of thousands were either turned away when they volunteered or simply passed over by the Selective Service when they became eligible for the draft.

Black recruits who actually made it into the military were often greeted by a racial nightmare, especially when they waited out the war in Southern camps. There they faced legendary cruelty from white officers who resented having to command them at all, as well as hatred and harassment from townsfolk who were more favorably inclined toward German prisoners of war than toward black Americans in uniform. By the middle of the war, maltreatment of black soldiers had spawned race riots on so many military posts that the Army seemed to be shaking itself to pieces.

African-Americans who lived through this humiliating experience have typically been hesitant to discuss it, and most have taken their experiences with them to the grave. The distinguished historian John Hope Franklin, now 91 years old, broke the silence thunderously in his memoir, “Mirror to America,” which offers a clear-eyed but also heart-wrenching portrait of one black family’s struggle to serve with honor in a nation that regarded them as less than fully human.

Dr. Franklin was a newly minted Harvard Ph.D. at the start of the war. Like most black intellectuals at the time, he was well aware of the nightmare life that awaited educated black men who were drafted into the Army. He hoped to escape that fate by “selling” himself to the Navy, which was desperate for men after the attack on Pearl Harbor. The recruiter seemed stunned as Dr. Franklin reeled off his qualifications, which included shorthand and typing (at 75 words per minute) as well as his doctorate. But the recruiter, he writes, “said simply that I was lacking in one important qualification, and that was color.”

He next turned to the War Department, which was hiring dropouts from Harvard to write the official history of the war. He submitted his qualifications, which included a book already in press, and even solicited support from the first lady, Eleanor Roosevelt, all to no avail. “I decided that they did not want to win the war,” he told me in an interview, “they wanted to win the status of white people in this country.”

His older brother, Buck Franklin Jr., had a different, and even worse, experience. He was drafted, despite being married, over 30 and a high school principal, by a bigoted draft board that seemed determined to bring an “uppity” black man down. Assigned to a white officer who appeared to have hated him from the start, he fell into a depression from which he never recovered. He died in 1947, after he either fell or jumped from a hotel window. Dr. Franklin, known throughout his career for his evenness of temper, still refers to his brother’s death as murder.

The forces of nostalgia see Jim Crow segregation as a minor blemish on the otherwise noble effort that was the great war. But government-enforced racism was actually at the very heart of the enterprise. It undermined the war effort, further poisoned an already racially troubled society and took a savage toll on families like the Franklins. It would be a crime in itself for the country ever to forget that.