[@Kafka Komedy] Well, he could probably get the legs regardless, but yes, that works well enough as justification. I ought to mention, for your sake and everyone else's, that chimeras as a race (or "race", depending on how you see things) are less than fifteen years existing, and the war probably less than five; unless James is a child soldier, chances are he wasn't born a chimera, since that'd be literally impossible unless he were younger than when they were initially discovered.

As for the RP's focus, I'd say mostly the exceptional members, i.e. the PCs. If you want to play as a faceless peon in one side's army, or even a generic civilian, feel free. Just be aware that you'll be dragged into the thick of things sooner or later. And at the mention of sides, it's perhaps worth bringing up that there'll probably be inter-factional disputes too, since "all humans" aren't exactly unified in the modern age, and I wouldn't necessarily expect perfect unity of that sort from any given race even several decades on from now.