Williamson Murray, professor emeritus of history at Ohio State University, on the notion that military failures can be traced to an overemphasis on the lessons of the last war:
It is a myth that military organizations tend to do badly in each new war because they have studied too closely the last one; nothing could be farther from the truth. The fact is that military organizations, for the most part, study what makes them feel comfortable about themselves, not the uncongenial lessons of past conflicts. The result is that more often than not, militaries have to relearn in combat—and usually at a heavy cost—lessons that were readily apparent at the end of the last conflict.
[Williamson Murray, “Thinking About Innovation,” Naval War College Review, Spring 2001, 122-123. This passage was cited in a recent essay by LTG H.R. McMaster, “Continuity and Change: The Army Operating Concept and Clear Thinking About Future War,” Military Review, March-April 2015. I recommend reading both.]
Actually, the Romans were very good at learning from their past mistakes.
Overglorification and wartime propaganda are sure of an anaesthetic though.