Daniel Headrick is celebrated for Tools of Empire, a wonderful book showing how technology delivered victory for Western imperialists in the nineteenth-century world. Now he has written an equally good book apparently undermining his own thesis. At least, Power over Peoples demonstrates the limits of technology and corrects widespread assumptions and misreading of the evidence by those who think that technical prowess ordained the rise of the West and condemned the rest to subjugation. The two books – superficially so different and, at first glance, in serious mutual tension – are really complementary. Together, Headrick’s work shows that tools for communicating commands, shifting armies, keeping white men alive in the tropics, and killing their enemies with unprecedented efficiency facilitated the global extension of Western empires, but did not constitute indefeasible superiority or guarantee success.

In part, Headrick’s switch of emphasis to the deficiencies and failures of technology is intelligible in the context of a widespread new skepticism, voiced most radically in the work of David Edgerton. It also reflects and accords with what has become a consensus, voiced especially by Kenneth Pomeranz, in favor of the role of contingency in explaining the shifting global balance of wealth and power. In part, too, Headrick´s current stance it is a function of the relatively longue durée the author now espouses, compared with the nineteenth-century focus of Tools of Empire. The new book begins in the fifteenth century, when Western technology was little different from, and in some respects inferior to, that of rival civilizations, and devotes nearly half the total space (four chapters out of nine) to the pre-industrial period.

Headrick points out how, among well equipped seafaring cultures of the period in which European overseas expansion began, “that of the Polynesians surely ranks first;” (p. 12) others on the shores of Asia exceeded Europeans in shipbuilding and navigation. Yet, for reasons that transcended technology, Spanish and Portuguese seafarers, followed by other Europeans, spanned otherwise neglected, globe-girdling routes.

In the first half of the book, the author´s judgments are always sensible, though his reliance on English-language sources makes some evidence inaccessible to him. He repeats, for instance, the misleading old cliché about the “research institute” of Henry the Navigator; evidently unaware of the work of Laguarda Trías, he is seriously out-of-date in his account of Columbus´s methods of navigation; and he accepts uncritically the mistaken notion that English ships “destroyed” the Spanish Armada.(p. 42) He is out of touch with much recent scholarship on European conquests in India and most of the Americas, underestimates, I think, the indigenous contributions to the maintenance of European empires in both regions, overlooks the impact of disease on the Spaniards and their allies in New World conquests, and makes some disquieting errors. Motecozuma, the Aztec paramount, for instance, was not “killed during the evacuation” (p. 107) of Tenochtitlan, nor was his successor, Cuauhtemoc, killed at the end of the siege. (p. 110) Nor is it accurate to say that spahis is “French for sepoys.” Both terms are naturalized in English, and derive from transliterations of an originally Persian term, respectively in Turkish and Urdu. Headrick´s overall conclusions, however, are surely right; that relatively simple technologies were often able to overcome more complex ones (a point re-emphasized throughout the book with reference to later periods); that the nautical environment and the disposition of winds and currents were more significant than technology in favoring European imperialism and long-range trade; that European supremacy was in any case late and fleeting; and that “politics, technology, and geography conspired to create a stalemate in Asian waters that lasted for three centuries.” (p. 88)

The core of the book, where the author´s expertise is highly reliable (though the map of the spread of empires in Africa on p. 279 is wrong in almost every particular), concerns industrial technology and the parts it played in the successes of European and U.S. imperialism. Headrick identifies three critical areas of accomplishment that were “necessary but not sufficient” (p. 2) for Western success: first, steam technology, especially in connection with navigation, where Europeans were able to buck environmental constraints and reach otherwise impenetrable zones of the world; second, medicine, where anti-scorbutics and such fever-depressants as quinine, especially, played a vital role in enabling Europeans to cross oceans and survive in the tropics once the appropriate treatments became available on an industrial scale. The last critically important item was weaponry: rifled guns, steel cannon, machine guns, long-range ballistics, and airborne weapons all, in turn, gave their possessors at least a brief advantage over under-equipped adversaries.

In this moiety of the book, Headrick´s contributions are often critical, surprising, counter-intuitive, subversive and overwhelmingly convincing. At every turn, he shows that Western technology suffered from serious shortcomings in the conflicts in which it was deployed. The trajectory of James Belich´s fine work on The New Zealand Wars (of which Headrick might have made more use) applies, it turns out, to many other colonial conflicts. Despite some challenging and persuasive observations on “the difficulties of transferring military technology from one culture to another,” Headrick makes it clear that technological superiority yields diminishing returns and is often easily emulated, or, as he points out in perhaps too brief a passage about Ethiopia, forfeited by over-confident aggressors. In fascinating pages on the diffusion of firearms, the author points out that they often represented a case of bad technology driving out good, because warriors in a variety of cultures prefer to sacrifice efficacy for security: thrusting-spears and bows were effective in the hands, say of Zulu impis or Native American marksmen, but longer-range weapons were attractive to fighters whom they spared from having to close with their foes.

When the author turns to the impact of air power and the disasters of latter’day colonialism in Vietnam, Iraq, and Afghanistan, his conclusions are candid, devastating, and cogent: “technological hubris,” he opines, “was a disastrous illusion” (328) for Westerners who thought they could bomb, shock or awe others into submission, and, surprisingly frequently – especially in the case of aerial warfare uncritically applied – “rather than helping win wars … helps lose them.” (p. 364)