Could all soldiers in the Roman army actually speak Latin?

Question

I am under the impression that men for the legions of the Roman Empire were conscripted across the empire, and so Latin could not have possibly been the first language to every soldier. But could all soldiers speak and understand Latin to some extent, or were some of the troops led in another language?

More concretely, are there examples of entire legions or perhaps smaller units of the Roman military that operated internally in a language other than Latin? Or are there perhaps mentions that the whole army operated entirely in Latin and all new conscripts had to learn it? I imagine that units of mercenaries would operate internally in their own language, but I want to focus this question on soldiers fighting in Roman uniforms. Even if the distinction is not meaningful, one can still ask: What were (some of) the most notable units of Roman military to operate in a language other than Latin?

Answer 1

As you note, the answers to this question will depend on the specific period of Roman civilization. Roughly, Latin fluency would be more common among higher social classes, more common in the West, and more common in earlier periods of the Empire. Latin was the language of command, and therefore normal soldiers would be able to understand it to that level, even if they didn't speak it otherwise.

We have archaeological evidence of military graffiti in Latin from various parts of the Empire - for example, in the second century, soldiers stationed at Hadrian's Wall were writing in Latin, as were others in Syria. The Syrian example also demonstrates graffiti in Greek and in a mixture of those languages. Since these texts are direct and unofficial, they are pretty good indicators of day-to-day military life. (Compared to seeing a tombstone in Latin - that's evidence of its official use more than its everyday use.) The actual examples of the language are dominated by personal names, or the names of legions and other units, but do include fragments of identifiable Latin grammar. So in this period, soldiers were writing short Latin phrases and expecting them to be understood - whether because they had it as a cradle tongue, or because it was a common language for soldiers of varied origins.

This matches with scholarly accounts based on Roman military writing, including those from much later periods (6th C. and later), where the general picture is that Latin was used for:

• many technical military terms (plus a little Greek)
• verbal tactical orders
• official bureaucratic writings

Broadly, this would enable Latin-speaking commanders to be understood by individual soldiers. But at that time, Latin was no longer a conversational language for most people in the East - they typically spoke Greek, even in the most elevated strata of society, and even for official purposes. The Strategikon, a military manual of the 6th C., notes that

a good number of Latin terms and other expressions in ordinary military use have been employed to make it easier to understand the subject matter

and gives examples of disciplinary formulae which were intended to be read out in both Latin and Greek. That all points to a world where one could no longer assume soldiers understood enough Latin to make sense of "don't run off and plunder the dead or you will be executed", but where Latin words and phrases were still normal for specific technical purposes and stereotyped commands ("attack now!").

Answer 2

According to the Languages of the Roman Empire Wikipedia article,

Latin was the official language of the Roman army until the mid-6th century, and remained the most common language for military use even in the Eastern empire until the 630s. [31]

This doesn't answer the question of what other languages were used and by whom, but it does suggest that conscripts to any legion would have been expected to learn Latin.

Answer 3

From a source-less stance, Roman foot soldiers must have spoken their dialect fluently and understood enough Latin to carry out certain group determined tasks (build bridges, forts, roads,...). Likewise for any foreign person involved in Roman military affairs.

I primarily articulate in English, but I also understand I do not know what is English; apart from some memorized intonations and grammatical structures, English is a style of sound popularly spoken in my time, as Latin must have been to Roman military personnel.

The requirement for Roman military personnel to communicate in Latin should have been necessary in order to be enlisted; however, the Latin fluidity of each Roman soldier should have varied.