Coming back again to the review, and this time it's this line in this comment that's sticking with me...

It's an almost contrarian statement to make about survivorship so soon after WWII—Zinnemann lost both of his parents to the Holocaust—and it still feels unusually adult three-quarters of a century later and the viewer isn't banged over the head with it, it's just part of understanding what happened between Frank and Joe, to both of them. Every time I see the film, the things it's real about amaze me.