In many military units, communication is of utmost importance and I would imagine that oftentimes there simply isn’t enough time to officially translate all orders and reports into the other official languages because a hostile tank is going to be at your location in 30 seconds and you have to act NOW, not worry about verb tense and selecting the appropriate vocabulary.
How do countries with more than one official language handle this with respect to their armed services? Does the Canadian Army have separate French and English speaking divisions, companies, platoons, etc., and soldiers are assigned to a team speaking their language? Does each team/platoon/etc. need a fully bilingual person to interface with other teams? Same thing with Switzerland - do soldiers join an Italian speaking division because Italian is their best language, or because while they are fluent in it as well as German, they prefer Italian or the army really needed another person to fulfill a role in an existing Italian speaking team?
The Spanish armed forces handle it like most people in Spain handle it: communication is mostly in Spanish, but if a group of people have another common language they can use it. This includes both official languages of the country and others which are not (such as Calé or English), and in any case other people may ask for a translation if they think they need one. A friend who’s in the army says his officers encourage conversation in English so they stay somewhat proficient, as so many of the assignments are international ones. Orders and their acknowledgements are always in Spanish.
Spanish forces are not divided by language or region. Some units tend to attract people from certain parts of the country (the mountain units are famously full of southern guys who had never previously seen snow), but it’s not by design.
South Africa has eleven official languages but English is the official language of the Defence Force (SANDF), even though it is a second language for most members.
The only rule about other languages is that it you should answer a greeting in the language it is offered in, but from there you can proceed in English.
The Vandoos (Veingt-Deuxs) are a famous french-speaking regiment of the Canadian military. A friend of mine recounts running into a bunch in the Korean War; he said they were crazy, they almost killed him. He walked into a tent while they were playing “hot potato” with a live trigger from a grenade, and the last fellow tossed it past him out the door just before it went off.
I suppose they are a big enough group that they can do most missions on their own, and the officers are bilingual enough to communicate with other english-speaking groups.
I think that many bilingual and multilingual countries have a system where soldiers from different language communities are given training in separate units in their own language, but the whole armed forces has just a single command language.
This is also how it works in Finland: the country is bilingual, and since only 6% are Swedish-speaking, the military uses Finnish as command language. In one of the units training is in Swedish, in all others in Finnish. The Swedish-speaking units form their own brigade, where longer orders, reporting and other communication are in Swedish, but all the commands are in Finnish just as in Finnish-speaking units. Here, commands mean those short orders, such as drill commands (attention, arms, rest, march, etc.) and field commands (fire, left, right, etc.), which need to be clear and unambiguous, and which is sufficient when Swedish- and Finnish-speaking troops are assigned together.
When drafted, people can choose which unit they would prefer. Especially in bilingual areas, quite a few Finnish-speakers choose to service in the Swedish-language unit to improve their language skills, and vice versa. The officers in those units most likely to cooperate are bilingual enough to handle the communication.
Historically Swedish had much more important role in the Finnish military. For many diverse reasons, Swedish speakers tended to be more likely to pursue a military career. Even after Finland got independent, when Mannerheim assumed the highest command of the white troops in the Civil War of 1918, he couldn’t speak any Finnish. Although he later learned a lot, during WWII the main language spoken in military headquarters was still Swedish. This posed some problems with the general who was second-in-command and couldn’t speak very good Swedish. According to some anecdotes, the communication in Finnish military HQ was therefore often in French.
In the Austro-Hungarian army, every soldier, no matter which of the empire’s 15 native languages he spoke, had to learn 68 basic military expressions in German. Officers were expected to learn the predominant language of their units. According to one story, though, Austrian officers and Ruthenian (the name given to the empire’s Ukrainians), communicated in English: the officers had learned it at university, the soldiers in anticipation of emigrating to the USA.