"Nearly a century of energetic effort to diagnose and treat PTSD
(including much recent attention to civilian victims, via accidents
or criminal assault), had made it clear that most troops eventually
got PTSD if they were in combat long enough. During World War II,
it was found that, on average, 200 days of combat would bring on
a case of PTSD for American troops."


"What the army does know is that a large percentage of its
combat troops have over 200 days of combat. Some have three
or four times that. A major reason for army generals talking about
the army "needing a break" (from combat) is the growing loss of
many combat experienced troops and leaders (especially NCOs)
to PTSD. The army won't give out exact figures, partly because
they don't have much in the way of exact figures. But over the next
decade, the army will get a clearer picture of how well they have
coped with PTSD, among troops who have, individually, seen far
more combat than their predecessors in Vietnam, Korea or World
War II."


See:

http://www.strategypage.com/htmw/hta.../20091011.aspx