Vietnam Veteran "Ron" had to work through the guilt concerning his buddy:

First he was ordered to call him on his wedding night, and give him two options:

He could return to base immediately, and get a few days of later to say good bye to his new wife, or he could stay for the night and then have to return without leave.
As soon as they got to camp, they were bombarded every night at 2:30am, which is the time he still wakes up in the morning.
The camp was completely unprepared, with plywood floors and no security, and they had no weapons to defend themselves.
The anger at the military not being prepared for them and keeping them safe was enormous.
Both he and his friend could do nothing but hide under the bed and wait.
While the soldier drank a bottle of scotch and smoked a pack of cigarettes, his friend helplessly cried and sobbed.
Seeing his friend, who had just gotten married a few days before, like that, was something he never got over.
Tapping on this memory helped him relax and release the tension.

This Marine also reported that some of the helpers in camp were Vietnamese, and they found out later that they secretly helped the VC. They pretended to be friendly, but their families were connected and they were working against them. So they were never safe.

Using EFT also helped to release those memories and the rage felt about them and get him a sense of peace.