[JonPreston]

The WWII victors GAVE parts of Germany to Poland after the war, kind of like reparations.

Please explain the legal mechanics of how this happened, with special attention to the "spoils of war" doctrine.

[ought-six]

Easy: In unconditional surrender the victors get to set the rules, and rearrange political boundaries as they see fit. It has ALWAYS been that way. Just look at the “realignment” after WWII: Entire empires disappeared.