I think that if you refer to the enormous introduction to John Keegan’s The Face of Battle, you’ll be able to track the citations which show S.L.A.M.'s observations on troops firing in anger to be erroneous. But I too am going to have to go to the vault to look that up, for the reasons I name below.
Going purely from memory (of Keegan’s work and other sources), I believe that Marshall’s observations sprung from his work on Makin Atoll, which I happened to ask about in another facet of this topic. In fact, in that thread zut and mhendo came to the mathematical conclusion that, if a triangular system of reserves was employed, and no reserves were committed, only about 20% of a division would actually see combat.
I would say that the 20% figure may have spawned from Marshall, except now I can’t find where Marshall said anything about reserves OR the number of troops who fired shots in anger.
Back then, I was bad enough to not provide any decent citations–I recall having trouble finding them. Now, our good friends at the DoD have put the final report on Makin online for us to peruse.
A quick review only provides a reference to “indiscriminate” fire in the Conclusion. But I also find no reference to the “triangular” reserve problem I asked about in that other thread. Obviously, I have to read it in full, but right now I’m wondering exactly where I learned the damned Marshall-reserves problem to begin with! The link above is to the final report, not Marshall’s work, which was “edited and partially rewritten.”
I’m thinking that the two issues may have shaken out like this: Marshall may have concluded that too many troops were held in reserve; the final report writers may have come to the conclusion that the real problem was too many soldiers firing indiscriminately at night. (I recall that after Makin troops were encouraged to use grenades rather than their rifles when night fighting.) The 20% firing myth may have also spawned from this very same issue.
Sorry to confuse the issue even worse. If I can find the time to look into this I’ll offer any answers I find.