What pivotal phenomena lead English to become the dominant language of the world?

The American Revolution, with subsequent American economic expansion

The British Empire was later and more expansive than the Portuguese or Spanish Empires. But the real spread of English occurred during World War II, with the rise of America as a super-power, and the collapse of old European colonies.

The Spanish, the British, and the Dutch all colonized America, however it was the British who had come to stay. The Spanish came to pillage, and the Dutch to trade. Therefore, I guess, as they claimed North America as their own (killing off the native Americans of course), the British spread English through the Bible, setting up what was to become a global super-power with English as their first language. So, in very simple terms, the British Empire followed by the American Empire has made English a world-wide language.

In addition to the British Empire and America becoming a superpower, there’s a third factor: the significantly smaller effort required to learn English compared to learning French, German and other languages.

I can think of several big things:

1) The success of the British Empire, largely thanks to the quality of its navy, and in some cases its armies, and their successes in their struggles in particular with the Spanish.

which led to:

2) The success of the British colonies in North America, and their subsequent revolution and independence, and acquisition of the Louisiana Purchase, and their genocide of the native American populations and dominance of the most usable parts of the entire continent, all under the English language.

which led to:

3) America’s size and resources and separation by oceans from Europe and Japan, allowing it to decisively support the Allies (including Britain) in the two world wars of the 20th Century.

and

4) The spread of English-language media (movies, music, written publications, advertising, television, other products with labels written in English) on a massive scale, which is consumed by most or all smaller countries.

The British Empire. God save the king.

I agree with @Zaku , but the outcome of the Cold War probably played some factor too?

Airplane pilots insisted on one universal language – theirs – American/English.

Yes. The defeat of the English armada instead of the defeat of the Spanish armada near Calais, France in 1588 would have given Spain control over England and we would probably all be speaking Spanish now.

@mattbrowne Is what you said about learning English provably true?
I thought Romance languages were easier to learn, especially Spanish. And after learning one, the others followed easily as the wor4ds and structure were similar.

@YARNLADY Why assume airline/airplane pilots spoke English predominantly?

@anartist I am not assuming any such thing – I am answering the question.

It’s not the dominant language of the world with respect to the number of native speakers and the number of countries using it, though it is popular.
It is in third place behind Mandarin Chinese and Spanish, and may drop to number 4 or 5 soon with the fast rise in population in India (Hindi) and Islamic countries (Arabic).
http://en.wikipedia.org/wiki/List_of_languages_by_number_of_native_speakers

The largest and most socially & economically dominant empires the world has ever seen:
the British and American.

Especially since they started working together.

@Zaku I totally didn’t realize your #4 made such a dent! Thanks!

JaneraSolomon, I think it IS dominant, in that it is the universal language used to communicate between peoples. How many millions of people who use Mandarin is kind of irrelevant… for now at least! English is not just popular, it’s the most useful and used language in present-day communication.
Mattbrowne, I disagree that it takes less effort to learn English. It has one of, if not the biggest vocabularies of all languages, constantly growing as it assimilates words from other languages. It might be more accessible than other languages, but I don’t think it takes less effort to study and learn English. If anything, I’d say it’s a pretty complicated language.

Maybe the English reproduced faster than any other nation.

@anartist and @Rheto_Ric – Of course there are many different kinds of complexities in languages. My native language is German, which makes it a bit easier to learn English compared to native speakers of Romance languages. I also learned French, Italian and Spanish in this order. Spelling is much easier in Italian and Spanish compared to English, and the same goes for pronunciation, especially when reading a text. Besides spelling, English is quite complex when it comes to the rules of verb tenses. Knowing the right prepositions is tough too, but the same is the case for Spanish and Italian.

There are two factors that make Spanish and Italian and French so much harder than English in terms of effort

1) Gender of nouns including the impact on adjectives
2) Conjugation of verbs

So let me rephrase:

For beginners it’s easier to learn English because it requires less effort to get started. To be able to master English on an advanced level, an enormous effort is required. It does indeed get complicated. One reason is the larger vocabulary, although this is less of a problem if one’s third language is French as in my case. But larger vocabularies don’t matter at the beginning.

Yeah, apart from there being common exceptions, English verb conjugation is extremely simple.

I’m learning Japanese, and inflection/conjugation was especially difficult to grasp at first, because natural English speakers don’t even realise most of these ‘cases’ exist, as English has no differentiation (WRT verb modification) between large swathes of them.

Gender is something I will probably always hate, and I can imagine myself continually refusing to memorize genders in German and the Romantic languages. The worst thing is that different languages have different genders for the same thing…

German requires the extra effort to distinguish between Dativ und Akkusativ for prepositions and verb objects. And this needs to be combined with gender and grammatical number. And it affects not only nouns but also adjectives, like

Ich gab meinem kleinen Bruder vier rote Kugeln.

The rules are quite simple actually. The problem is forming correct sentences on the spot, applying the rules again and again and again. Your brain will burn extra glucose like crazy. Until it becomes automatic.