What a story.
I don't say good luck to my 10 year old when he is about to take a test. Nor do I wish anyone luck who is about to do something requiring effort for which they either did or did not prepare. War is not like that. You need to be prepared, and preparation and experience do a lot get you through combat. A lot of times, however, it really does come down to chance. Call it luck, karma, fortune, whatever - sometimes people’s luck just runs out. I recall the scene in Band of Brothers where the 88mm shell lands right in front of the two troopers and just fizzles. Some German guy back in the fatherland forgets to connect a couple of components in a fuse and you live; he does it right - you die. This sort of explains why fighting men have been such a superstitious lot since early times. Nothing else as serious is quite like it. There but for the Grace of God. . .
So to all of our friends in harm’s way today, I wish you good luck.