score:3
During WW2 you had:
Upvote:2
In the Russian Civil war of 1918-21, the incorporation of prisoners was so standard operation that some people changed sides many times. They had to choose from being shot or dying from starvation in the camp, against maybe remaining alive by means of "voluntary" incorporation. Such mass incorporations happened practically after every battle. Not three examples, but millions of them.
Upvote:3
In the American Civil War, both sides recruited from their POWs. Most entered US service and smaller number of Union POWs entered Confederate service. See https://en.wikipedia.org/wiki/Galvanized_Yankees