It seems to me that the AI upgrades most of his Squad Infantry to Marines as soon as they become available. In the semi-late game the AI has Machine Gun and Marines for infantry, no Squad Infantry. This seems a little weird and is probably due to the nerfing of Infantry (from 20:strength: down to 18:strength:) and always the upgrade path from Squads to Marines. Is this worth looking into?

I agree. It seems a little odd to me that Infantry upgrades into Marines. I liked that Marines were infantry that were specialized against machine guns and for sea-based assaults. I did appreciate the Squad Infantry nerf, but it just didn't feel right that they upgraded into Infantry. Same gripe I have against Paratroopers upgrading into Special Forces.

The AI doesn't use Motorized Inf?

The AI doesn't use Motorized Inf?

I think maybe they are talking about the time before motor infantry opens up. It is quite a bit from the time industrialism to mass media.

Yes, we are. Motorized Inf does show up later, but for a long time most of the AI infantry is just Marines, and a few Machine Guns. Regular infantry should be sufficiently attractive for the AI to continue building even after Marines become available.

I wonder if this has been addressed in the most recent version. Squad Infantry still upgrades to Marines, according to the Pedia, but I haven't played into the Modern Era, so I don't know if the AI eventually turns them all into Leathernecks.