A common critic we hear about an EU wide army is What language are they gonna speak but let’s forget Europe 2024,

Rome had a huge empire over the whole Europe, I may be wrong, but I don’t think that commoner spoke proper Latin in remote province. What happens when they join the legion ? Would the units be split by origin region (Dacian with Dacian, Lugdunumese with Lugdunemese) with only officer speaking latin ? Or would you merge legionaries from different province (So you have Tingitanian, a Lustitanian and a Thracian in the same unit) and give them a crash course in military latin (the way the french foreign legion does? ) Even going as far as Rome, Karl the great empire also spread over half of Europe, and modern European nation used to be way more multi-lingual than they are today, and most likely a random southerner/northerner in Britain, France or Germany couldn’t talk to each other.

So how did ancient armies managed the language question ?