: Well, as far as I'm aware, the UEG only took shape AFTER the Interplanetary
: War was won by the UN. So that means the war was fought by the UN and its
: UNSC. I haven't read the literature in a long time,though, so I'm not
: sure.

Did a quick Halopedia brush up... at the out of the IP war, yes the UN consolidated the Earths militaries creating the UNSC. Then immediately following the Callisto Treaty, the UN formed the UEG.

My search also reminded me that there was already bioaugmenting of soldiers happening in the IP Wars, hundreds of years before ORION