Nope. Factorys work fine with lots of immigrants with minimal english.
Armys in spades back when mercenarys were the main source of troops.
Even in WW2, the Italian army worked fine even when so many Italians couldnt understand other Italians. The problem with the Italian Army wasnt the language, it was that they were gutless.
Same with the Germans with so many Hungarians, Romanians etc involved with them.
BULLSHIT.
The english civil was was never about accents.