A bit of drift here but my grandfather was a first world war soldier. He spoke no French but was fluent in English although Gaelic was his mother tongue. The Eastern Townships of Quebec were settled by many Highland Scots in the mid 1800's and at the time of WW1 they were French speaking but some still understood at least some Gaelic and he was able to communicate with them in the language of their ancestors although they had no English. Cape Breton plays Gaelic fiddle so maybe someday at least three barriers can be overcome by fiddle music!