Explain the execution. (Chapter 17)

From the text:

“These are the men responsible for the bullet holes in your foot. It’s time to make sure they never shoot at you or your
comrades.” The lieutenant pointed at the prisoners. I am not sure if one of the captives was the shooter, but any captive would do at that time. So they were all lined up, six of them, with their hands tied. I shot them on their feet and watched them suffer for an entire day before finally shooting them in the head so that they would stop crying. Before I shot each
man, I looked at him and saw how his eyes gave up hope and steadied before I pulled the trigger. I found their somber eyes irritating."