Some (Gabriella Blum not among them) cite the following incident (mentioned in Blum's 2009 article as quoted below) as evidence of an enemy spared by the humanitarian instincts of the poet and mythologist Robert Graves (one of my favorite authors on myths):

In Just and Unjust Wars , Michael Walzer ([1977] 2006, 143) famously takes on the question of the Naked Soldier, first raised by Robert Graves (1929) in his memoir Good-bye to All That : Is a soldier stripped naked and swimming in the lake a legitimate target during an armed conflict? The answer, says an uncomfortable Walzer, is unequivocally “yes.”
My recollection of Graves WWI memoirs, Good-bye to All That, was that the event was less than humanitarian. Lo and behold (at p.132) we find it - and a discussion of individual and collective risk:

Like everyone else, I had a carefully worked out formula for taking risks. In principle, we would all take any risk, even the certainty of death, to save life [of a comrade] or to maintain an important position. To take life we would run, say, a one-in-five risk, particularly if there was some wider object than merely reducing the enemy's manpower; for instance, picking off a well-known sniper, or getting fire ascendency in trenches where the lines came dangerously close. I only once refrained from shooting a German I saw, and that was at Cuinchy, about three weeks after this. While sniping from a knoll in the support line, where we had a concealed loop-hole, I saw a German, about seven hundred yards away, through my telescopic sights. He was taking a bath in the German third line. I disliked the idea of shooting a naked man, so I handed the rifle to the sergeant with me, 'Here, take this. You're a better shot than I am.' He got him; but I had not stayed to watch.
Whatever this might be, humanitarianism it was not.

Graves was one of four Royal Welch Fusilers who wrote WWI memoirs of note. The others were Siegfried Sassoon (3 vols.), Frank Richards (2 vols.) and J.C. Dunn (a thick Bn history). The last includes extensive excerpts by Clifton Stockwell aka "Buffalo Bill", who was the "officer in charge" of the RWF's segment of the 1914 "Christmas Truce". Stockwell was a fine soldier (a coy, bn and bde commander), who went to bat for his men with higher commands; but who had an abrasive personality - e.g., "I never remember him having any favorites: he treated all the men the same way - like dirt"; and "... an absolute pig if you got the wrong side of him."

Regards

Mike