So part of your question is touching on the concept of a Lingua Franca--a common language to conduct business, commerce, and diplomacy--within a world of multiple languages. Throughout history there have been different linguae francae(plural of lingua franca), like you mention Latin for the Roman Mediterranean, but also Greek for Hellenistic Eastern Mediterranean. This also applies outside of the "Western" world, as Arabic became a lingua franca where their religion and empire expanded--from the Iberian peninsula to North Africa to the Indian subcontinent. I have quoted the word Western since Edward Said, in his book Orientalism, has discussed the dyadic relationship between the West and the East and how colonial powers often otherized the East--by making it exotic, erotic, and primitive--in order to define and raise their own perceptions of themselves. This leads me to the more modern/recent aspect of your question. Both French and English are relative linguae francae due to their large imperialistic landholdings. This age of imperialism, starting in the 1800s and lasting into the 20th Century, saw large swaths of the world come under the direct and indirect control of European powers. For further reading see Thomas Pakenham's The Scramble for Africa ISBN 9780349141930 0349141932. This control developed a common language amongst the people colonised, as they needed to be able to speak the imperial language in order to advance within that system. This is why places like Nigeria and Algeria still speak English and French, respectively, in their business and administrative realms. Britain also has a commonwealth system that is a whole other factor/digression.

Another aspect to consider is the idea of eras of peace guarded or policied by specific powers. This idea of Pax Romana, Pax Britannica, and Pax Americana. The first describes the era of relative peace in which the core of the Roman empire experienced relative peace and little external threat due to Rome's military prowess. See more with Adrian Goldsworthy's Pax Romana: War, Peace and Conquest in the Ancient Era ISBN
9781474604376 1474604374. Pax Britannica lasted from 1815-1914; this is because the British Coalition had successfully defeated Napoleon's final attempt for power--thus ending the Napoleonic Wars--and ended with the start of the First World War. While there remained warfare during that time--see the many colonial wars, such as the Boer Wars, Boxer Rebellion, even the Spanish-American War and the Crimean War, etc.--peace within mainland and Western Europe remained. This again can be looped back with the concept of Orientalism, as what is considered important/a time of peace to some is dictated by those holding the power. The British also maintained the largest naval force at the time and could utilize their navy to protect their holdings and also deter outside interference from other colonial powers. See Rebecca Berens Matzke's Deterrence through strength: British naval power and foreign policy under Pax Britannica ISBN 9780803235144 0803235143. Finally, the Pax Americana began after the Second World War, as the United States remained the only Allied power with not only its infrastructure intact, but also footed to produce the resources needed by Europeans to rebuild. That is why the US still views itself as the international police force, because for years after the Second World War they remained what they perceived as the only bastion of Democracy and Capitalism that could effectively defend the world from fascism and then communism.

I hope this sufficiently answers your question. It kind of meandered but I am mostly a historian of British/Australian imperialism, with a decent understanding of general imperialism and Military History from Napoleon through the Cold War. I am more than willing to provide additional sources or information if any of the above piqued your interest.