A fairly enjoyable work covering the so-called great powers from 1500 to 2000 (it was published in 1989). Some passages I highlighted:

1. But China had a habit of changing its conquerors much more than it was changed by them, and when the Ming dynasty emerged in 1368 to reunite the empire and finally defeat the Mongols, much of the old order and learning remained.

(this interested me as I was reading the Old Testament and noted how often the prophets vituperate the Israelites for conquering the surrounding semitic tribes and then promptly adopting their customs & gods; it seems a paradoxical result of conquest, that the conqueror is culturally subsumed by the conquered).

2. […] but what was clear was that it was going to be extremely difficult for other societies to ascend the ladders of world power when the more advanced European states occupied all the top rungs.

This difficulty would be compounded, it seems fair to argue, because moving up that ladder would have involved not merely the acquisition of European equipment or even of European techniques: it would also have implied a wholesale borrowing of those general features which distinguished the societies of the West from all the others. It would have meant the existence of a market economy, if not to the extent proposed by Adam Smith then at least to the extent that merchants and entrepreneurs would not be consistently deterred, obscured, and preyed upon. It would also have meant the existence of a plurality of power centres, each if possible with its own economic base, so that there was no prospect of the imposed centralization of a despotic, oriental-style regime – and every prospect of the progressive, if turbulent and occasionally brutal, stimulus of competition. By extension, this lack of economic and political rigidity would imply a similar lack of cultural and ideological orthodoxy – that is, a freedom to inquire, to dispute, to experiment, a belief in the possibilities of improvement, a concern for the practical rather than the abstract, a rationalism which defied mandarin codes, religious dogma, and traditional folklore. In most cases, what was involved was not so much positive elements, but rather the reduction in the number of hindrances which checked economic growth an  political diversity. Europe’s greatest advantage was that it had fewer disadvantages than the other civilisations.

(My supposition is that as military technology becomes increasingly complex, requiring a larger support network of high-IQ technicians & engineers, effective weaponry will be only truly available to medium-to-high trust, high-IQ nations. Low-trust, medium-to-high-IQ nations like China or Russia can develop advanced weaponry but – well, Chernobyl, and Wuhan.)

3. But perhaps the greatest military advantage possessed by the Habsburgs during these 140 years was the Spanish-trained infantry. The social structure and the climate of ideas made Castile an ideal recruiting ground; there, notes Lynch, “soldiering had become a fashionable and profitable occupation not only for the gentry but for the whole population.” In addition, Gonzalo de Cordoba, the “Great Captain,” had introduced changes in the organization of infantry early in the sixteenth century, and from then until the middle of the Thirty Years War the Spanish tercio was the most effective unit on the battlefields of Europe. With these integrated regiments of up to 3000 pikemen, swordsmen, and arquebusiers, trained to give mutual support, the Spanish army swept aside innumerable foes and greatly reduced the reputation – and effectiveness – of French cavalry and Swiss pike phalanxes. […] it is significant that Spanish power visibly cracked only in the mid-seventeenth century, when its army consisted chiefly of German, Italian, and Irish mercenaries with far fewer warriors from Castile.

(as with the Roman Empire, once they began to outsource their military, recruiting from conquered tribes, the game was up; imperial strength rests on financial and military capability, and the latter depends on the manpower (demographics) of the folk)

4. In the last few years of Elizabeth’s England, or in Philip II’s Spain, as much as three-quarters of all government expenditures was devoted to war or to debt repayments for previous wars. 

This is a recurring theme – even seemingly hegemonic empires like Spain are massively in debt, spending everything they have on their military. I’m not sure if it was always so, but certainly one gets the sense that most of the great powers are plunging headlong to their own financial ruination. Only the money-lenders profit from empire; and it seems a risky business even for them.

5. Just as the Austro-Hungarian Empire was distracted by having to grapple with a number of enemies within Europe, so British statesmen had to engage in a diplomatic and strategical juggling act that was literally worldwide in its dimensions. In the critical year of 1895, for example, the Cabinet found itself worrying about the possible breakup of China following the Sino-Japanese War, about the collapse of the Ottoman Empire as a result of the Armenian crisis, about the looming clash with Germany over southern Africa at almost exactly the same time as the quarrel with the United States over the Venezuela-British Guiana borders, about French military expeditions in the equatorial Africa, and about a Russian drive toward the Hindu Kush.

There seems a natural limit to power, as it necessitates increasingly complex responsibilities; at some point these become unmanageable.

6. For all the ambitions of London and Paris (and, later on, China) to join the nuclear club, this striving during the early post-1945 decades was somewhat similar to the Austro-Hungarian and Italian efforts to possess their own Dreadnought-type battleships prior to 1914. It was, in other words, a reflection of weakness rather than strength.

Technology drives human affairs; once a weapon has been developed, it is not possible to do without it – even if the nation must bankrupt itself in the pursuit.

The book becomes inevitably amusing as it makes future projections from the late 1980s. Thus, Kennedy:

Just how powerful, economically, will Japan be in the early twenty-first century? Barring large-scale war, or ecological disaster, or a return to a 1930s-style world slump and protectionism, the consensus seems to be: much more powerful. In computers, robotics, telecommunications, automobiles, trucks, and ships, and possibly also in biotechnology and even in aerospace, Japan will be either the leading or the second nation. In finance, it may by then be in a class of its own. 

Kennedy also makes some astute observations:

By far the most worrying situation of all, however, lies just to the south of the United States, and makes the Polish “crisis” for the USSR seem small by comparison. There is simply no equivalent in the world for the present state of Mexican-United States relations. Mexico is on the verge of economic bankruptcy and default, its internal economic crisis forces hundreds of thousands to drift illegally to the north each year, its most profitable trade with the United States is swiftly becoming a brutally managed flow of hard drugs, and the border for all this sort of traffic is still extraordinarily permeable.

But even Kennedy could not envisage the ruin brought upon American military-industrial capacity through decades of liberalism:

More narrowly, there could be serious implications for American grand strategy if its industrial base continued to shrink. Were there ever to be a large-scale future war which remained conventional (because of the belligerents’ mutual fear of triggering a nuclear holocaust), then one is bound to wonder what the impact upon U.S. productive capacities would be after years of decline in certain key industries, the erosion of blue-collar employment, and so on. In this connection, one is reminded of Hewins’s alarmed cry in 1904 about the impact of British industrial decay upon that country’s power:

Suppose an industry which is threatened [by foreign competition] is one which lies at the very root of your system of National defence, were are you then? You could not get on without an iron industry, a great Engineering trade, because in modern warfare you would not have the means of producing, and maintaining in a state of efficiency, your fleets and armies.

It is hard to imagine that the decline in American industrial capacity could be so severe […]

In 1989, Kennedy would, I dare say, have been surprised to learn that American would proceed to outsource much of its military technology to China, and much of its blue-collar manufacturing to the 2nd World, including Mexico; and that even Republican US politicians would welcome mass illegal migration from Mexico, until there could be as many as 30 million illegal migrants voting Democrats across the US.

One could see the Ascent of Donald Trump as the natural counter to such developments.