How many U.S. Navy 'battlefield' promotions are you aware of? I spent considerable time in the Navy, during the same period as Cooper, and I don't recall a single one. If you know of some, share them with us.
My boss was in PBRs in Vietnam (if you ever see The History Channel's documentary on the PBRs, he's on there, talking about his experiences), and there were a bunch during his tour alone, and a ton of awards for valor, including one man who was awarded the Medal of Honor. (The man who received The Medal passed away last year from lung cancer in South Carolina--he was the most decorated living sailor before his death. Unfortunately, his name escapes me at the moment.)
The brown-water Navy was a LOT different from the rest of the Navy--more like the Army or the Marines.