Pat Tillman was killed by "friendly fire". As I understand it, it was an accident. By the way, it makes him no less of a hero in my humble opinion. Friendly fire incidents are also known as fratricide. The Army teaches soldiers how to fight side by side. When one digs a foxhole, one of the considerations is who and where are the soldiers to the left and to the right. The idea is that you don't want inadvertently shoot the soldier to the left or right of your position. Likewise, you don't want them to shoot you either. This is not only true of individuals, but also true of each unit. The platoon needs to know which platoons to the left and right of its own position. The same is true of each larger unit too; company, battalion, brigade, division, etc... The idea is to reduce fratricide and work as a team. Even when people are doing all the right things fratricide still occurs.
Reading "Stories of Emergence" I noticed that a lot of the issues are about hurt and angst. It seems from the tones that they are victims of friendly fire and at times they they too turn their weapons to toward their brothers. I'm guessing that they are not aware that they are doing this. I'm not sure of the answer of how to help without making it worse.