The truth of war, the war on truth, and the unconquerable spirit that unites them.

Ms. Gower-Alton in character as the late Sunday Times correspondent Marie Colvin in Matthew Heineman's "A Private War." Paul Conroy / Aviron Pictures

Putting on an eye patch does not make you feel like a pirate.

At first, it feels like an eye exam. Your uninhibited eye searches for some writing, somewhere, on which to focus. Can you read it? Yes, of course you can. Is that a B or an E? It's an E.

Then you're disoriented. Dizzy. Your head aches somewhere behind your open eye and the bridge of your nose, extends backward. You will probably need to lie down.

I wore an eyepatch most days over the course of two months in an effort to portray the late Marie Colvin. Ms. Colvin, an American journalist and war correspondent for The Sunday Times, became known for wearing one in the last decade of her life, the result of an injury from a rocket-propelled grenade attack in Sri Lanka.

It was not an artistic decision on my part to wear the patch as much as possible, even when I wasn't being filmed – it was necessity. I had to learn to do it all, as Ms. Colvin did fifteen years before, or there would be no hope of embodying her.

At first, I could not walk straight while wearing it, let alone run and sail (two personal pastimes of mine, and skills I use in the film). Eventually I learned not to miss my mouth when smoking the cigarettes Ms. Colvin often did.

Of course, I only wore my eyepatches on film sets in Jordan and England, doing a job for which I am handsomely paid and in which I have the luxury of asking to call "cut." Marie Colvin wore hers to bear witness to conflict across the globe, including the string of Arab Spring uprisings in 2011 that ultimately led to her death by improvised explosive device in Homs, Syria, in 2012.

There is a deep responsiblity in bringing someone so devoted to unyielding truth-telling to a larger audience, a heaviness barely tapped by the physical gauntlet of learning to exist with one eye closed. My conviction is hardly what hers was, my humanity hopefully a fraction of hers. But while I had a lot to learn from her, I had more to learn in the process of preparing for the challenge – about war, about truth, and about our duty to each other.

We too often take any barrier to entry – an eyepatch, if you will – as a handicap. We explain away ignorance as blindness, excuse lack of knowledge as the result of the many hindrances to having full knowledge, see the deduction of tangible truth as a Sisyphean task, and our fear of being wrong so great that we do not even try.

How can you possibly understand something – really understand it – if you don't have the full picture?

But you do not need both eyes to see clearly. Marie Colvin didn't.

With practice, you can train the eye you do have, and we all must. Our vision will never be perfect (whose is?), nor complete, and the process will be uncomfortable, but in an age where the truth-tellers of war are under attack, the reality of it obscured, and a war on truth itself raging, we cannot afford to let difficulty lead to total blindness.

HRH The Duke of Sussex, Patron of the Invictus Games Foundation, cheers on competitors at the UK team trials for the Invictus Games Toronto 2017 in Bath, England. Chris Jackson/WPA Pool via Getty Images

Since 2016, I have served as an ambassador for the Invictus Games, an international adaptive multi-sport event for wounded, injured or sick armed services personnel and veterans.

Since 1982, I have myself been the daughter of a serviceman, now a veteran. I have been alive a shorter period of time than my father served my country.

One thing you learn early on in speaking with those in the military is that you will never understand the scope of the stories they share. This is even more apparent when the person has seen combat, yet more when injuries are involved – let alone the injuries you cannot see. I credit a lifetime surrounded by active and veteran seveicemembers with my ability to listen, my perspective on the world, my understanding of responsibility to fellow man.

It is tempting to stare wide-eyed at these rightfully vaunted men and women who protect and defend us, to hold up their sacrifice as other. And wouldn't the alternative, to try and take our own personal problems as ways to relate to those who've been injured or traumatized or both for a cause that's greater, be insultingly reductive? We will never have objective understanding of that which they endured. Nothing close. Why try?

And yet, it is human to want to be understood. What becomes clearest when you listen to servicemembers is a desire not to be put on a pedestal, to not only be listened to but properly heard, for their words to be processed in the way all others' are, regardless of the weight of it.

Much of this is what inspired my friend The Duke of Sussex, himself a war veteran, to bring the Invictus Games to the world stage. His Royal Highness saw the value in honoring those who have served us through celebrating them in sport, literally cheering them on as they put the determination, teamwork, and spirit that define military service on display in new ways.

Sport is powerful, and physical pursuits can be compelling and restorative for bodily and mental health. But more than that, sport is something we all share. It is a plane on which we can all have the equal footing of sportsmanship, the collective joy of victory, communal comfort in defeat. And if we can find one thing we share, we can find another.

In order to find another, we must see it.

Our men and women in uniform face unspeakable horror and tragedy to defend us, but they are not in a vacuum. Those carrying weapons and the flags of their countires can inflict as much terror as they can prevent, even in the pursuit of that prevention, often in greater measure. They come home from war still bearing the responsibility of the preservation of human life and freedom, and the burden of having failed others in the act.

We may never understand it, but we can find ways to relate and help our servicepeople cope only if we have the tools. Those tools come from people like Marie Colvin.

Her reporting illuminated for the world what conflict really looks like, unvarnished and raw, vicious, deafening. Somewhere between militant and civilian, she was able to break through with the one thing both of those populations shared. Somewhere in the midst of shrapnel and flares and tear gas, she bore witness to the truths of war, lost an eye to open ours.

Like many soldiers, Ms. Colvin came to experience the mental horrors of armed conflict, and the physical scars it leaves behind.

Like the civilians caught in the large-scale crossfires on which she reported, Marie Colvin was collateral damage.

An image from the theatrical trailer for "A Private War." Jérémie Laheurte (L) portrays the late French photojournalist Rémi Ochlik opposite Elizabeth Alton (R) as Marie Colvin. Image courtesy Aviron Pictures

The truth is that many war reporters are. There is some dispute about the nature of Ms. Colvin's death in particular – her family has filed suit against the Syrian Arab Republic for what they believe was a targeted assassination of Marie and her photographer, Rémi Ochlik – but even setting aside her death in particular leaves a list hundreds of names long of journalists killed in conflict, their lives lost in pursuit of illuminating the truth for the rest of us.

There are also many journalists killed out of conflict zones. Just this week we are witnessing what is a likely an attempted coverup of the killing and dismemberment of Saudi journalist Jamal Khashoggi at the hands of his own government. The fact that this threat to journalists transcends theatres of war can only imply that it is not about the war – it is about the truth.

Colvin herself said, "The public have a right to know what our government, and our armed forces, are doing in our name. [Journalists'] mission is to speak the truth to power."

That right to know is crucial to our roles as global citizens. The existence of war is upsettingly chronic, and if we are ever to mitigate its effects, or even end it, then empathy is our greatest asset – empathy for those fighting, and for those fought around and over. To assert that journalists are enabling the knowledge to which we all have a right is not intended as a thinly-veiled threat to weak would-be autocrats, trying to hide government actions domestically and abroad from their constituents. It is necessary. It is truth itself. There is nothing fake about the act of bearing witness, nor transmitting what can be readily seen by those brave enough to watch up close, even with only one eye.

The truth can be painful, and often is. War and conflict have faces, and it is easier to look away than to run toward that reality. That which we most need to know is also the most difficult to hear, let alone see. And because it is so seemingly unfathomable, because the trauma of war seems grave and other, we are able to avoid looking it in the face because how dare we try to understand?

But the human spirit has a neat ability to turn to teflon when you least expect it. The spirit of soldiers, that of war correspondents, that of civilians in conflict zones – and yes, that of the rest of us – rises to the occasion. How lucky are we?

Out of the night that covers me,
Black as the Pit from pole to pole,
I thank whatever gods may be
For my unconquerable soul.

In one private visit with Invictus competitors, I came to speak with a young man who had lost the lower half of his leg to an IED in Afghanistan. He was hoping to compete in sailing at this year's Invictus Games in Sydney. We spoke at length about our love of the sport, both of us having learned to sail from our fathers.

We were talking about the escapism of sailing when he paused, and said, "I needed to keep sailing, especially on the days when it hurts the most. Wouldn't you hate to let pain win?"

Marie Colvin in Chechnya in 1999. She was acknowledged by her peers as Britain’s foremost war correspondent. Photograph: Dmitri Beliakov/Rex

It is a question I often ask myself. I live with chronic pain, and it is on the days when I most struggle to get out of bed that I feel most strongly about following through. It may not be a surprise that I am what many would call a "workaholic" – but to borrow this young man's words, I need to work when it hurts the most. I would hate to let pain win.

It felt fraudulent to be honest with him, to call my discomforts "pain" when in the presence of life-altering injury, the result of horrific suffering I pray I never understand. But it would be to deny another person humanity to arbitrarily withhold my truth from him on the basis that his sacrifices were greater than mine.

After all, in order to even approach understanding, you must first have truth.

"I would," I replied, before adding, "I do."

He took my hand and said, "Me too."

I am reminded now more than ever that small acts of unity, even those that feel infinitesimal or trite, even and especially those carried out through a little discomfort, propel us towards truth, that common truth that is greater than yours or mine. Current events can feel unrelenting – the conflict in which Marie Colvin died is still ongoing – but something that is shared by those in conflict zones and the journalists that follow them and dispatch home to the rest of us is an abiding spirit reinforced by the knowledge that our shared humanity is worth it, that giving us all the chance to see those affected by inhumanity as human is a worthwhile cause.

Which brings me back to Marie Colvin, and her eyepatch. One eye can take over for both. Maybe it would be easier to fall back on what is imperfect, to write off faults as a result of living with one eye necessarily closed. The path through our shortcomings may be difficult, dizzying, may even feel punishing. But we still have the ability to see – differently, incompletely, but no less truly. We must take understanding into our own hands, and protect those who enable us to do it. The truth is sacred, those who tell it and those who live the worst of it included. It is our responsbility not to forget it.

We are the masters of our fate, and the many truths to power.