: Okie dokes, here's my half-assed thinking: The UEG even throughout the
: Interplanetary War and the conflicts that preceded it wasn't the totally
: united entity that it became post-war and throughout the millennia. It was
: more like a United Nations that had its shit together. However, that
: doesn't exclude the fact that this slightly more interconnected body of
: nations wasn't dominated totally by the foremost national powers.

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.

: The warfighting capability of UEG that beared down on the Friedenists and
: Koslovics in these conflicts across the Sol system were likely
: substantially provided by such nations like America, Britain, France, the
: People's Republic of China, and Russia. Each of them would have likely had
: their own space-faring forces and the capability to sustain their own
: extraterrestrial settlements.

That is definitely correct. What I'm not sure about is China and Russia, though.
The Koslovics were communist, so that would mean that Communist China either fought against them as part of the UN, stayed neutral due to their communist sympathies, or left the UN outright and supported the Koslovics. Though the latter would have added the additional threat of a China-UN ground war on Earth, with possibly nuclear implications, so I don't think that's plausible.

As for Russia, I have some doubts that they'd support a US-led UNSC, but I don't think they'd have any choice.

Or perhaps China and Russia in 2160 are no longer anti-US. Perhaps China isn't even Communist anymore. We can only speculate since we know literally almost nothing about this period.

To anyone from 343 Industries who might be reading this: PLEASE provide more literature on this period! Yes, we history buffs are a minority in the Halo fan community, but throw us a bone!

: So, in the case that the UEG had not won the Interplanetary War, there's
: quite a bit that would certainly change, but much would be the same. Earth
: would still have the greatest economical, military and political
: capability, and their drive to use it would have only sparked more
: interest within her nations to marginalize their victors. Technology,
: however, might possibly jump forward with more substantially weaponized
: starships and perhaps slipspace drives being introduced sooner to gain
: that critical edge in battle. As such, you would see more interstellar
: endeavors being undertaken much sooner than had actually happen.

Actually, that makes complete sense, yes. Similar to Germany after the defeat of WW1 -- they started a raging militarization campaign with the sole objective of destroying the victors. Germany failed at that endeavour, but nevertheless.