This Memorial Day will mark 75 years since World War II entered its most pivotal phase. On this day, in 1944, as Allied forces were preparing to invade Normandy and push millions of German soldiers back across Europe, American Marines and soldiers were locked into a ferocious campaign against the Japanese, storming the beaches of one blood-soaked island after another.

The devastation and brutality of that war, and the astounding scale of human loss, has been well-documented in literature and film. We rightly pay tribute every Memorial Day to all who have worn the uniform, conveying our boundless gratitude to those who have fought to defend our great nation. Yet many of these returning war heroes, particularly those among the World War II generation, have never felt — not for one day — like heroes. Beneath steely façades and uniforms adorned with decorations for valor, were sometimes broken men. Men whose souls and spirits had been profoundly shattered by their wartime experiences.

In the post-war years, scores of such veterans with psychological wounds struggled to integrate back into their jobs and reconnect with their loved ones, haunted by the savagery and human carnage seared into their memories. They endured a form of emotional suffering borne by soldiers for generations, but one that remained verboten to acknowledge or speak of.

Post-traumatic stress is part of our lexicon today. Veterans advocacy groups, prize-winning books, advances in psychiatric medicine, and even a few well-made Hollywood productions have all contributed to greater public awareness. This heightened understanding has, in turn, driven policy changes that have provided recent returning veterans with access to services critical to managing what can be a crippling condition. Absent from much of this discussion, however, has been the impact of post-traumatic stress on previous generations.

Consider a high school senior in 1942. On a Saturday afternoon, he and his sweetheart take in a matinee of Wake Island, a Paramount Pictures film hastily produced just months after the attack on Pearl Harbor about a tiny, isolated Pacific island with a vital air base, 2,500 miles from Hawaii. The movie dramatizes the true story of what happened on Wake in the days following December 7 when a small garrison of underequipped Marines and civilian construction workers staged a valiant, ill-fated stand against a vastly superior force of Japanese invaders. Our young moviegoer watches a hand grenade sail across the screen, followed by the square-jawed hero disappearing in the ensuing explosion and cloud of smoke. This is 1942, so on film, his uniform is nearly bloodless, and his death quick, with little gore or suffering.

A year later, the young man is now a Marine himself, crouching under the gunwale of an amphibious landing craft piloted by an equally youthful Navy coxswain, churning towards the shores of Tarawa, another obscure Pacific atoll, where the enemy awaits. Five thousand Marines landed on the beach that first morning, and by the end of the day, a third of them were dead or wounded. Our young Marine, if he survived, would have witnessed a firestorm of wartime violence that would wreak havoc on any human conscience. Artillery shells indiscriminately pulverizing men to bits while spraying others with deadly shrapnel. Machine gun fire pouring onto the beach, tearing apart the Marines, their corpses riddled with large-caliber bullets. Detached limbs, shredded torsos, and so many other repulsive sights, punctuated by the piercing, agonizing screams and moans of the wounded and dying, their pleas for relief and quarter echoing across the sand and jungle.

If this sounds grim and gruesome, you bet it is. Those men endured absolute hell, and what a price they all paid, as even those who survived were left forever tormented by images, sounds, and memories the human brain is simply not wired to absorb.

In the months that followed the surrender of Germany and Japan, combat veterans, as well as former prisoners of war who suffered a different form of misery, poured back into the United States by the hundreds of thousands. They were ardently cheered in their hometowns, but over the decades, a mythology began to take hold. A notion that this “Greatest Generation” was comprised of supermen of sorts. Citizen-soldiers who paused their lives to answer the call to duty and defend their country, and when it was over, simply shed their uniforms, pulled on their work boots, and filled the factories and enterprises that fueled the post-war boom for years to come.

Much of this is true. But lost in this glowing narrative are the great numbers of war veterans who quietly agonized, their post-war lives consumed with horrifying memories that could never be shed. They came home to an America still basking in triumph from the war, but anxious to heal and press forward into a more peaceful and prosperous era. An era when rampant stigmas and misconceptions about mental illness prevailed. Open and frank discussions about mental health were wholly alien then, and so these veterans clammed up, pulling themselves into the darkest of corners. For many, their lives became marked by violence, alcoholism, divorce, and suicide.

Several years ago, I wrote about my own brother’s struggle with mental illness. An illness that took his life. I will never forget the public reaction to that piece, and the responses from so many friends and strangers who shared with me stories of loved ones coping with depression and anxiety, some more successfully than others. I was overwhelmed by all I heard, and came away with one inescapable conclusion. Mental illness is far more pervasive — even today — than we are willing to acknowledge and discuss in the open. Year after year, it destroys those we love. And despite our relative enlightenment compared to past generations, we continue to refuse to confront and draw awareness to it with the same resolve and gusto as we have for so many other diseases that have plagued the health of our country.

If this is the state of our enlightenment in 2019, consider what war veterans experienced in 1968, 1945, and 1918. On this Memorial Day, we will continue the tradition of honoring our returning soldiers with parades, medals, and endless praise. All very much deserved. But we must add to that an eternal remembrance and gratitude for all that they have sacrificed, which is often far less visible than any physical wounds they may bear.

Award-winning author and writer from Arlington, Virginia.