Most people coming out of a war feel lost and resentful. What had been a minute-to-minute confrontation with yourself, your struggle with what courage you have against discomfort, at the least, and death at the other end, ties you to the people you have known in the war and makes, for a time, all others seem alien and frivolous. Friends are glad to see you again, but you know immediately that most of them have put you to one side, and while it is easy enough to say that you should have known that before, most of us don't, and it is painful. You are face to face with what will happen to you after death.

My vengeance is my guilt

MY REGRETS ARE ABOUT THE PEOPLE I COULDN’T SAVE — Marines, soldiers, my buddies. I still feel their loss. I still ache for my failure to protect them.

Great is the guilt of an unnecessary war.

When we apologize for something we’ve done, make amends, or change a behavior that doesn’t align with our values, guilt — not shame — is most often the driving force. We feel guilty when we hold up something we’ve done or failed to do against our values and find they don’t match up. It’s an uncomfortable feeling, but one that’s helpful. The psychological discomfort, something similar to cognitive dissonance, is what motivates meaningful change. Guilt is just as powerful as shame, but its influence is positive, while shame’s is destructive. In fact, in my research I found that shame corrodes the very part of us that believes we can change and do better.

I felt a sense of shame like a burning ulcer. This was not guilt: guilt is what you feel when you have done something wrong. What I felt was shame: I was what was wrong.

Shame on military glory, shame on armies, shame on the soldier's profession, which changes men, some into stupid victims, others into base executioners. Yes shame, that's true – but it's too true, it's true in eternity, but not yet for us.

I feel guilty for being a member of the human race.

Guilt is often an emotion we carry from childhood and then project onto current circumstances when we felt as though we were burdens to those around us.

The victims of PTSD often feel morally tainted by their experiences, unable to recover confidence in their own goodness, trapped in a sort of spiritual solitary confinement, looking back at the rest of the world from beyond the barrier of what happened. They find themselves unable to communicate their condition to those who remained at home, resenting civilians for their blind innocence.
The Moral Injury, New York Times. Feb 17, 2015

Guilt starts as a feeling of failure.

​Blaming our actions rather than our character allows us to feel guilt instead of shame.

It was the shame we knew so well, the shame that drowned us after the selections, and every time we had to watch, or submit to, some outrage: the shame that the Germans did not know, that the just man experiences at another man's crime; the feeling of guilt that such a crime should exist, that it should have been introduced irrevocably into the world of things that exist, and that his will for good should have proved too weak or null, and should not have availed in defense.

People generally don’t suffer high rates of PTSD after natural disasters. Instead, people suffer from PTSD after moral atrocities. Soldiers who’ve endured the depraved world of combat experience their own symptoms. Trauma is an expulsive cataclysm of the soul.

The Moral Injury, New York Times. Feb 17, 2015