What was the fate of the Marines in Halo ODST/New Mombasa?
The Army would have probably been wiped out as they were the first lines of defence. The Air Force obviously has aircraft and spacecraft, so can fly away. But the fate of the marines isn't fully clear to me. We do see various marine bodies alongside flares throughout Mombasa Streets. I expect the majority of the marines we meet in ODST all belong the the same one or two units, as I doubt Dutch would away move from the unit he landed next to, and would travel with them. They all head (or try to head) to the ONI facility anyway, and Mickey was with the same group heading there, and at the facility. All the Marines Buck meets die (as they all seem to become scripted one-shot after a certain point). So all these Marines probably die.
Obviously this can't be all the Marines in the city. So, what happens to the other Marines (and indeed Police Officers) that didn't make it to the ONI facility in time, (or were cut off trying to get there)? We're told that every marine in the city is heading there, so some must have survived. Afterall, from what I can remember, in Kizingo Boulevard there are several openable doors sometimes with living Marines inside that don't make an effort to go with you, like the one at the large end Wraith area operating a second Gauss turret on one of the buildings. Surely the UNSC wouldn't leave them all to die, even if there is no remaining command structure? If they did, that would mean that only Alpha 9 and those that went to Delta Halo survived the engagement, which seems unrealistic.
I may have missed something really obvious, but I don't think so?
Edit: Just remembered that Reynalds references being in Mombasa in Halo 3. Presumably he escaped then at some point, so maybe others did with him?