That's a very good question.
Veterans are a little different on this subject. Some will feel that they need to be supported by people who can fully understand their situation. They will therefore benefit greatly from peer support, from people to whom they don't need to explain a lot of things. It's a protective network. However, other veterans, upon leaving the armed forces, feel the need to distance themselves from the military and their comrades in arms. In their case, the support would be very different and would instead involve helping them create a network in the civilian world that would provide them with support.
I've seen both, but peers can certainly play an important role. The problem, at least among the generation of military members I've treated, is that these people don't talk about these things much among themselves, or don't dare to talk about them, when they could sometimes offer each other valuable support if they were at least able to talk about them.