English is the NATO language.

The Eastern Europeans have some troubles with English because the older soldiers (40+) didn't learn it at school.

The French are often rather reluctant to learn English.

The Franco_German Brigade may benefit of the fact that Alsace and Lorraine - the two French border provinces - have a mixed history and many inhabitants who know German (about a Third of the adults know a German dialect). I'm not informed how well the French exploit this opportunity.