What does Eddie tell his wife that happened to him during the war?

Eddie tells Marguerite that he had lost himself during the war.

"What happened?" she asked. "During that war?"

He had never quite told her. It was all understood. Soldiers, in his day, did what they had to do and didn't speak of it once they came home. He thought about the men he'd killed. He thought about the guards. He thought about the blood on his hands. He wondered if he'd ever be forgiven. "I lost myself," he said.