Thanks, I can't recall ever seeing that word before.
No anecdote comes to mind relating to such people -- not in some American army, anyway.
Your example here of Pickett's charge suggests maybe "file closers" were not all that effective, when the chips were down.
Is there evidence of "file closers" in the Union Army?
If so, how were they used?
If not, why not?
file closers were used in both armies, but they had different degrees of authority.
In the confederate army, they were directed to use deadly force. There were some regiments in the US Army where the regimental commander gave such orders, but they were not considered
http://www.acws.co.uk/nl/nl0701/fileclosers.htm
Article on file closers.
Ordering file closers to shoot their own soldiers was not considered a good position to have on paper. Lee was unusual in that he put it on paper in his General Orders Number 4. Military Police were to apprehend deserters, not, not to shoot them.
Rather like the sad fact that the original major purpose of the Marines was to protect navy officers from the conscripted or impressed enlisted men. Once the volunteer navy happened, that purpose for the Marines was much diminished.