It started with the rise of the British Empire. Pax Americana just helped solidify it. Even without an English speaking US, English would be about as popular as Mandarin: there are a billion Indians.

> there are a billion Indians

That is true... but only 10% of Indians can speak English. It might appear higher because visitors are likely to remain in urban or tourist-y areas, where the percentage of English speakers is much higher.

China also has many topolects. Only two thirds of Chinese speak Mandarin as first language.

English still has a lot of influence over India, though. I think this thread is confusing influence with supremacy, English has had a huge influence on other languages and cultures for centuries.

Yes, after WWII. Einstein still published his key papers in German (1905), https://en.wikipedia.org/wiki/Annus_Mirabilis_papers

I would absolutely not say that. The British Empire encompassed more than a quarter of the population, and in the 1870s the US became the world's largest national economy.

I think what you're thinking about is when English supremacy started, that can probably be dated to the post-WWII world when the US economy was far ahead of everyone else for decades.

The influence started with the rise of the British Empire. Obviously English wasn't dominant at that point the way it is now, but still internationally influential.