The spread of European empires beginning in the 15C overtook the heretofore limited frame of reference. Larger and more powerful fleets connected an increasing web of footholds and colonial holdings. As the field of operations increased, the centuries-old dynastic dynamics of European politics started to play out in far-flung locations. The Seven-Year’s War (1756-63) pitted British, French, Spanish, Prussian, and Austrian forces in Europe against each other, as well as the navies and colonies of the first three in the Western Hemisphere (North America and the Caribbean), Southern Africa, and the Indian Ocean. There were intermittent echoes during the (French) Revolutionary and Napoleonic Wars (1791-1815), but the long peace which followed the Congress of Vienna made the wars of the 19C (even if European-inspired) relatively rare and localized.
The war that began in 1914 grew out of the mare’s next of the declining power of the Ottoman Empire in SE Europe. A combination of rigid thinking, alliances, and technology (not least of which was communications) quickly spun the assassination of Archduke Franz Ferdinand into a continent-wide conflict involving all the European Great Powers. Given the absence of overseas Austrian colonies, and the spotty nature of German holdings (four locations in Africa, plus a handful of South Pacific Islands) there wasn’t really much reason to conceive of the war as global conflict.
There was one notable exception to this framing: the ability of the Brits and French to mobilize their imperial resources—both men and materials—as part of the “total war” mentality which now seized the nature of modern warfare. It was a sign of globalizing perspectives—the roots of what we now see as normal supply chains and integrated trading and financial and labor markets.
But of course, they (i.e. the folks at the time) didn’t call it a “world war.” It was “the War” or “the Great War.” The adjective “World” wasn’t added until afterwards and didn’t gain currency until the 1930s. The use of “First” only grew as the likelihood of a “Second” loomed larger..
Whether the “Second” was separate from or merely a (long-truce-) interrupted continuation of the “First” was debated from the outset of the “peace.” Certainly the palpable global scale of the “Second” solidified the worldly appellation of the “First.” There are other framings of continuity as well, both backward and forward looking.
From history we can look at the interconnection between major geopolitical events which, in terms of amassed power and degree of interconnection were centered on Europe and the Atlantic beginning in the 16-18C: the American offshoot of British culture, the incremental revolution by which middling sorts and commercial elites replaced hereditary monarchs from the late 18C to early 20C), the rise of concentrated physical power (aka the industrial “revolution”). From this perspective, the demise of four empires in the course of WWI (German, Austro-Hungarian, Russian, Turkish)—while never “inevitable”—certainly fits within trends. The upsets of that war in Europe—cultural, economic, demographic, political—echoed across and cracked open the remaining formal empires (British, French), although they would take a further 30-50 years to collapse. This first global war of the 20C was fought in old terms: “liberal democracies” vs. stale monarchies in the last gasp of the Ancien Regime.
The socio-economic ideologies around which the First War was nominally structured were already melting. Globalization was accelerating (although the war set it back for thirty years), by the 1930s, socialisms had sat at the top table in Britain, France, Germany, and Russia and that strange beast of American ideas and energy was awakened.
All of these faced-off when modern fascism combined with old-fashioned territorial imperialism as Germany and Japan rolled the dice against the US/UK/Russia. Japan’s Axis with Germany and Italy (don’t forget Italy!) ensured that this time, the “World” was at war, as air and naval technologies allowed both sides to project power to every corner. From an economic perspective, the Axis didn’t stand a chance. Even beyond productive capability, the idea of territorial occupation as an effective means of permanent control was an idea straight out of the 15C: it couldn’t work in a nationalist/democratic/globalizing world; but fortunately, we never had to see their world view tested in practice.
The Allies’ triumph put international fascism by the boards, although a range of domestic varieties continue to pop up. The Soviet Union mangled Marxian economics and made one last stab at a territorial empire only to prove that there actually was something to Lenin’s critique of imperialism and his expectation that the natural path to socialism would take centuries.. It turned out that the “internal contradictions” of soviet communism were more dire than those of centrifugal capitalism. The US, now realizing that it could dominate the global economy without a formal empire, proved that a bureaucratic economy was no match for capitalist dynamism. It was a “cold” war at least as between the two champions, even if often “hot” in many places around the world; proxies on each side ensured that the nuclear confrontation could be kept theoretical (even if a brooding omnipresence).
By the end of the 20C, “liberal democratic capitalism” had beaten (or at least outlasted) monarchism, fascism, and communism. Geopolitics caught its breath for a decade. By now, thirty-something years later, we can see that the old models of how the world works are best consigned to the dust bin of history. As for what’s happening now…it’s too early to tell.