Expert on warfare Quincy Wright generalized on what he called "universal empire"--empire unifying all the contemporary system:
Balance of power systems have in the past tended, through the process of conquest of lesser states by greater states, towards reduction in the number of states involved, and towards less frequent but more devastating wars, until eventually a universal empire has been established through the conquest by one of all those remaining.
German Sociologist Friedrich Tenbruck finds that the macro-historic process of imperial expansion gave rise to global history in which the formations of universal empires were most significant stages. A later group of political scientists, working on the phenomenon of the current unipolarity, in 2007 edited research on several pre-modern civilizations by experts in respective fields. The overall conclusion was that the balance of power was inherently unstable order and usually soon broke in favor of imperial order. Yet before the advent of the unipolarity, world historian Arnold Toynbee and political scientist Martin Wight had drawn the same conclusion with an unambiguous implication for the modern world:
When this [imperial] pattern of political history is found in the New World as well as in the Old World, it looks as if the pattern must be intrinsic to the political history of societies of the species we call civilizations, in whatever part of the world the specimens of this species occur. If this conclusion is warranted, it illuminates our understanding of civilization itself.
Most states systems have ended in universal empire, which has swallowed all the states of the system. The examples are so abundant that we must ask two questions: Is there any states system which has not led fairly directly to the establishment of a world empire? Does the evidence rather suggest that we should expect any states system to culminate in this way? ...It might be argued that every state system can only maintain its existence on the balance of power, that the latter is inherently unstable, and that sooner or later its tensions and conflicts will be resolved into a monopoly of power.
The earliest thinker to approach the phenomenon of universal empire from a theoretical point of view was Polybius (2:3):
In previous times events in the world occurred without impinging on one another ... [Then] history became a whole, as if a single body; events in Italy and Libya came to be enmeshed with those in Asia and Greece, and everything gets directed towards one single goal.
Fichte, having witnessed the battle at Jena in 1806 when Napoleon overwhelmed Prussia, described what he perceived as a deep historical trend:
There is necessary tendency in every cultivated State to extend itself generally... Such is the case in Ancient History ... As the States become stronger in themselves and cast off that [Papal] foreign power, the tendency towards a Universal Monarchy over the whole Christian World necessarily comes to light... This tendency ... has shown itself successively in several States which could make pretensions to such a dominion, and since the fall of the Papacy, it has become the sole animating principle of our History... Whether clearly or not--it may be obscurely--yet has this tendency lain at the root of the undertakings of many States in Modern Times... Although no individual Epoch may have contemplated this purpose, yet is this the spirit which runs through all these individual Epochs, and invisibly urges them onward.
Fichte's later compatriot, Geographer Alexander von Humboldt (1769 -1859), in the mid-Nineteenth century observed a macro-historic trend of imperial growth in both Hemispheres: "Men of great and strong minds, as well as whole nations, acted under influence of one idea, the purity of which was utterly unknown to them." The imperial expansion filled the world circa 1900. Two famous contemporary observers--Frederick Turner and Halford Mackinder described the event and drew implications, the former predicting American overseas expansion and the latter stressing that the world empire is now in sight.
Friedrich Ratzel, writing at the same time, observed that the "drive toward the building of continually larger states continues throughout the entirety of history" and is active in the present. He drew "Seven Laws of Expansionism." His seventh law stated: "The general trend toward amalgamation transmits the tendency of territorial growth from state to state and increases the tendency in the process of transmission." He commented on this law to make its meaning clear: "There is on this small planet sufficient space for only one great state."
Two other contemporaries--Kang Yu-wei and George Vacher de Lapouge--stressed that imperial expansion cannot indefinitely proceed on the definite surface of the globe and therefore world empire is imminent. Kang Yu-wei in 1885 believed that the imperial trend will culminate in the contest between Washington and Berlin and Vacher de Lapouge in 1899 estimated that the final contest will be between Russia and America in which America is likely to triumph.
The above envisaged contests indeed took place, known to us as World War I and II. Writing during the Second, political scientists Derwent Whittlesey, Robert Strausz-Hupé and John H. Herz concluded: "Now that the earth is at last parceled out, consolidation has commenced." In "this world of fighting superstates there could be no end to war until one state had subjected all others, until world empire had been achieved by the strongest. This undoubtedly is the logical final stage in the geopolitical theory of evolution."
The world is no longer large enough to harbor several self-contained powers ... The trend toward world domination or hegemony of a single power is but the ultimate consummation of a power-system engrafted upon an otherwise integrated world.
Writing in the last year of the War, German Historian Ludwig Dehio drew a similar conclusion:
[T]he old European tendency toward division is now being thrust aside by the new global trend toward unification. And the onrush of this trend may not come to rest until it has asserted itself throughout our planet... The global order still seems to be going through its birth pangs ... With the last tempest barely over, a new one is gathering.
The year after the War and in the first year of the nuclear age, Albert Einstein and British Philosopher Bertrand Russell, known as prominent pacifists, outlined for the near future a perspective of world empire (world government established by force). Einstein believed that, unless world government is established by agreement, an imperial world government would come by war or wars. Russell expected a third World War to result in a world government under the empire of the United States. Three years later, another prominent pacifist, Theologian Reinhold Niebuhr, generalized on the ancient Empires of Egypt, Babylon, Persia and Greece to imply for the modern world: "The analogy in present global terms would be the final unification of the world through the preponderant power of either America or Russia, whichever proved herself victorious in the final struggle." In 1951, Hans Morgenthau concluded that the "best" outcome of World War III would be world empire:
Today war has become an instrument of universal destruction, an instrument that destroys the victor and the vanquished ... At worst, victor and loser would be undistinguishable under the leveling impact of such a catastrophe... At best, the destruction on one side would not be quite as great as on the other; the victor would be somewhat better off than the loser and would establish, with the aid of modern technology, his domination over the world.
Expert on earlier civilizations, Toynbee, further developed the subject of World War III leading to world empire:
The outcome of the Third World War ... seemed likely to be the imposition of an ecumenical peace of the Roman kind by the victor whose victory would leave him with a monopoly on the control of atomic energy in his grasp... This denouement was foreshadowed, not only by present facts, but by historical precedents, since, in the histories of other civilizations, the time of troubles had been apt to culminate in the delivery of a knock-out blow resulting in the establishment of a universal state...
The year this volume of A Study of History was published, US Secretary of State John Foster Dulles announced "a knock-out blow" as an official doctrine, a detailed Plan was elaborated and Fortune magazine mapped the design. Section VIII, "Atomic Armaments," of the famous National Security Council Report 68 (NSC 68), approved by President Harry Truman in 1951, uses the term "blow" 17 times, mostly preceded by such adjectives as "powerful," "overwhelming," or "crippling." Another term applied by the strategists was "Sunday punch."
A pupil of Toynbee, William McNeill, associated on the case of ancient China, which "put a quietus upon the disorders of the warring states by erecting an imperial bureaucratic structure... The warring states of the Twentieth century seem headed for a similar resolution of their conflicts." The evoked by McNeill ancient "resolution" was one of the most sweeping universal conquests in world history, performed by Qin in 230-221 BC. Chinese classic Sima Qian (d. 86 BC) described the event (6:234): "Qin raised troops on grand scale" and "the whole world celebrated a great bacchanal." Herman Kahn of the RAND Corporation criticized to an assembled group of SAC officers their war plan (SIOP-62). He did not use the term bacchanal but he invented on the occasion an associating word: "Gentlemen, you do not have a war plan. You have a wargasm!" History did not completely repeat itself but it passed close.