"The subjunctive mood was irrelevant to the conquest of Gaul"

Sometimes, people attributes the growth of English into a global language to its values intrinsic to the language. However, the idea is a bit simplistic, lopsided, overlooking the external influence that the language has undergone, such as military, political, economic, and cultural forces:

Compared with Latin, a sort of global language in the Middle Ages, Baugh and Cable write:

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It is often noted that Latin as the language of an empire was not hindered in its spread by the grammatical declensions of five cases for its nouns or by the complex conjugations of its verb. The subjunctive mood was irrelevant to the conquest of Gaul. (8)
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I like the way he puts it, "the subjunctive mood was irrelevant to the conquest of Gaul."
Here, "the subjunctive mood" represents the very complexity of Latin verb declension, while "the conquest of Gaul" is military dominance achieved by the Roman proconsul Julius Caesar against Gallic tribes (58 BC to 50 BC).

Baugh and Cable claims that both are not related to each other, which means "no matter how complicated the innate linguistic features are, any language can become the world language depending on the external factors such as military power and politics.

It is difficult to guess what the English language will be like in the future. In a short term, English might be unconquerable.

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Works Cited:
Baugh, Albert C. and Thomas Cable. A History of the English Language. 6th ed. London: Routledge, 2013.