Leeneia, I am in the middle of editing a bit, fat book (not my first by a long shot) that is full of gun battles, but I have never seen or heard one described as "rolling".

If the combatants are moving while fighting -- for example, a convoy of vehicles is ambushed on the road, and the drivers try to escape the attack but the ambush force chases them -- the fight could be described as a "running" gun battle. Another form of running battle is one in which one group follows another, attacking whenever the target group moves into an area that gives the attackers some advantage and laying off when the target group finds cover.

"Rolling" gun battle sounds like a journalist messing with "running" battle, probably out of ignorance.

Your post raises a bigger issue, however. In your last line, you imply disapproval of any description of abhorrent behaviour that does not state that it is abhorrent. As an editor who specializes in military subjects, I must disagree.

When discussing abhorrent behaviour, the good writer does not write, "This was awful". It is far more effective to describe the event and let the readers figure out for themselves just how abhorrent it was. (Journalists say, "Show, don't tell.") The book I'm working on right now is about the war in Afghanistan, and it is full of bombs that killed civilians, including children. If the author wrote, in every mention of an IED strike (there are hundreds) that it is a heinous act of indiscriminate cruelty, readers would quickly get the idea that the author's first priority is to demonizing the IED-layers. Frankly, that is not interesting. Also, it's not the point.

I don't read much about the Holocaust any more -- I think I know enough about it after more than 50 years of studying war and its effects -- but, even when I was young and revelations of the Nazi program still had some novelty, the accounts that dwelt on the heinousness of the whole thing were the weakest. The most effective works focussed on why it happened and how, and discussed the cost to the perpetrators and those who supported them as well as the victims.

Of course, even the most abhorrent events must still be reported and studied, although it is difficult to read about them. Otherwise, they would slip into the rear-view mirror of our culture and we might forget all about them.

Writing about violence is very difficult. It is easy to slip into gore-porn, or to indulge in propaganda and fantasies of revenge -- that's the big challenge of both war journalism and military history. An account written while the memory is fresh will be full of passion, and the purple prose that comes from it, but opinions change as time passes, the emotions may seem inappropriate, and the purple prose can become distasteful.