where the term "lingua franca
" came from?
In the late 19th Century and the early 20th century, the worlds largest colonial and economic power was France. Dont laugh, please - you'll offend the Francophones.
As the economic power of a people rises, so does their language and culture. Anybody who seriously traveled abroad (back then, not many people), even us Yanks, knew French. This is also why your passport has French on the inside cover. Even movies (pre talkies) were mostly made in France - The nice thing about silent movies being that translation is a lot easier.
But just before and during the world wars, France went into every kind of decline you can think of. With the United States and the United kingdom leading the remaining allied forces that eventually defeated fascism (both in the world wars and the 1980s) English became the language of choice for international commerce and business. But like the French, and even the mighty Romans, this too shall pass. No people will ever hold the language of another people above their own, for long.