It depends.

Man on man, and if both forces are of equal number (USMC is much much larger), legion would surely win, as they are definitely harder and better infantry soldiers.

 

Note I said infantry fighting.

Because in reality, if you put the USMC, even on equal numbers, vs the legion, you have to bring with you: USMC technology (most advanced in the world), USMC combined arms, and overall USA industrial might.

 

So in a realistic scenario USMC would crush not only legion, but would crush the entirety of France on its own without even the help of the airforce or the Army, in my honest opinion.

 

The strength of the USMC is not the individual soldier, which is more than often (except the crack troops) an average american who complains too much, but the WHOLE. The USMC as a WHOLE is a *team* that is the most elite warband of the world. Because of technology, because of tactics unrivalled in the 21st century, and so on.

 

But again, you take the *average* marine and the average legionnaire, put them in a cage with only bare hands, the legionnaire wins. But this is not how wars are waged. Nobody cares if you are "harder", only if you win. Legion would not even get close to USMC troops before they get wiped out by advanced tanks, drones, marine light airfighters, automated guns and targeting system that can blow you out to hell without you even knowing its out there and so on.