Additionally, there a re a number of international conventions that require English to be the "official" language.
In my own field of aviation, the international governing body is ICAO... International Civil Aviation Organization.
They determined in the Convention of Chigaco in 1944 to make English the official language. (Strengthen by Amendment 164 to Annex 1). No matter where we fly, the air traffic controllers (and pilots) must be English fluent.
I find that term to have a lot of different interpretations, however, especially with the emergence of China and other Asian countries in the commercial aviation world.
Additionally, French has, historically, been the language of diplomacy. In fact, the United Nations still recognizes French in that capacity. Many passports are still issued in French and the language of the holder. Canada requires every official document to be in English and French, but that's more of a regional neccessity...