I can't speak for the facts of the story, since I didn't write it. And I have no clue about what individual incidents the writer based the song on. Poetic license is often used by song writers to make a point (see the thread about "Jack Haggerty" in this forum, for instance).
However, if you know anything about the British military you will know that many unofficial attrocities were committed by the officers in charge of the fighting men in order to keep them in line. (A good novel on this theme,based on the facts, is Laurie King's Justice Hall, which deals with the British military practices during WW I.) My guess is that a lash on the face would be one of the lesser evils practiced by the Britsh military at war(or any military force for that matter).

I think what the song does do is paint a fairly accurate picture of the unpleasantness of war. War is crazy and unpredictable and often brings out the worst (and occasionally the best) in people. And it is entirely possible, though not a given, that the writer is in possession of facts that never made it into the history books. Wouldn't be the first time.

I do think that songwriting should reflect the truth-- but often it is a tool for propaganda, ax-grinding or expressing of personal opinions. Still I also judge a song on its literary and musical merits-- this one is good on both counts-- and sometimes a Truth can be expressed when the truth isn't being expressed. The fact that "Jack Haggerty" is not only "made up", but misleading, doesn't stop me appreciating it or singing it. For those who have loved and lost, it's a song that is very relevant.

I would be interested to have a first hand account of the writing of it, Jim, would you know how to reach Don? (I haven't checked out your links but will.)

Bekki