Didn't mean the armies, it was those that settled and stayed on the land, the army had taken, doubt many of those land owners and farmers bothered learning the local language, if they did they wouldn't speak it when they arrived.
How many of those leaving the UK to settle in Spain or France went speaking the languages? I think the vast majority that come not speaking English work hard learning it and ensuring their children are educated and speak English,whereever in he world they have come from..