hanna_anders German was the scientific language for quite a long time, it's never been a "world language" like French or English or Spanish because Germany never really had an overseas empire. the war has nothing to do with it.
You are fully coming right about the science language. As far as I know, there was a vote after the War of Independence in the USA whether English or German should be the official language and it turned out very narrowly for English.
But now very quickly back to topic, before Angelina gets angry