Historians may well come to see 2007 as the year when all the febrile post-Cold War, post-September 11 debate about a "new American empire" peaked and began to subside. Both the global dreams and the local power of the US neocons falter and fade; calls for a rapid exit strategy from Iraq become more strident; allies from Tony Blair to Australia's John Howard are toppled; and warning signs of instability and underlying weakness in the US economy accumulate. If there has been an early 21st-century "imperial moment", it looks increasingly possible that it will prove to have been momentary indeed.
That "moment", though, has already generated a quite astonishingly large and diverse literature. The past few years have seen ever more attempts to place recent world events in broader analytical, or deeper historical, perspective. Writing about empires commands a kind of global attention that it has almost never before had. And if this sometimes involves a short-sighted search for "lessons from history" for political use, it may also mean that even a book so seemingly far distant from current concerns as Judith Herrin's wonderful Byzantium: the Surprising Life of a Medieval Empire (Allen Lane, 20) is read by more people, and in a different way, than would have been likely a few years ago.
It might be either delightful or dispiriting to imagine eager young politicos searching Herrin's pages for soundbites applicable to America's present. But if they do, perhaps they'll learn some richer, less obvious lessons: not least hints of how the Byzantine imperial system, supposedly in decline almost from its first day, nonetheless managed to endure 1,000 years.
The hunt for historical analogies, parallels or even parables illuminating contemporary events also pushes one to think about the potential, and the pitfalls, of wide-ranging comparative history. We have seen an unprecedented outpouring of attempts to write a truly global history of empire, trying to integrate the stories of a huge range of imperial designs across the ages. Possibly the most resourceful and exciting of all is John Darwin's After Tamerlane (Allen Lane, 25), spanning six centuries since the 1405 death of the semi-legendary Mongol conqueror and, crucially, taking the whole Eurasian landmass, not just Europe, as its central focus. Only a little less capacious, and shifting emphasis from continents to oceans, is JH Elliott's monumental comparative study of Britain's and Spain's empires in the Americas, Empires of the Atlantic World (Yale, 14.99).
Thinking in terms of an "Atlantic world" leads to the role of sea power in history, especially British history and to the darkest of all aspects of oceanic interchange, the Atlantic slave trade. Both themes have preoccupied numerous new books: the latter partly prompted by the bicentenary commemoration of Britain's 1807 slave-trade abolition, the former with less obvious causes. One guesses, though, that the phenomenal popularity of Patrick O'Brian's naval fictions has something to do with it. Certainly, the world of Jack Aubrey and Stephen Maturin has engrossed the authors of several major studies. The outstanding example is Noel Mostert's The Line Upon a Wind (Cape, 25), a stunning panorama of naval warfare from 1793 to 1815 and a worthy successor to Mostert's South African historical epic, Frontiers.
This year also saw Brendan Simms's forceful, massively-documented Three Victories and a Defeat (Allen Lane, 30). It argues that we should not overstate the centrality of empires and oceans to British history, but remember that continental Europe was always more important. Among new works on the slave trade, the most original and compelling is Marcus Rediker's The Slave Ship: a human history (John Murray, 30). Approaching similar themes from a very different angle that of a philosophically saturated literary critic is Ian Baucom's Specters of the Atlantic (Duke, 15.95). Some will find Baucom's esoteric language offputting, but the range and sharpness of his insights make it worth the effort.
Equally worth the struggle is Duncan Bell's The Idea of Greater Britain (Princeton, 26.95). Historians of Britain's empire have increasingly revived such notions as "Greater Britain" or "the British World". Some, like Niall Ferguson and Andrew Roberts, have used such terms as launch pads for absurdly ahistorical hymns to the unique virtues of the English-speaking peoples. Bell's book, as a serious investigation of how that language was developed in the Victorian era, is a quietly powerful corrective.
Almost all these books focus on the rise and power of empires, or on the ideas and actions of imperialists. It's equally important to understand how empires end, and the beliefs of those who fought against them. In relation to modern American power, there has been a woeful neglect of the latter, except by way of simplistic pseudo-questions, mostly directed at Muslims on the lines of "Why do they hate us?" Thus it's enormously valuable to recall anti-imperialist traditions in American history. The Wilsonian Moment just after the First World War is reconstructed by Erez Manela (Oxford, 17.99), who argues that Woodrow Wilson's championing of self-determination opened the way to eventual decolonisation. Manela probably overstates his case, but this is an important work. In loosely parallel fashion, Philippa Levine, in the latest of numerous general outline histories of The British Empire (Longman, 17.99), gives more attention than most such surveys do to the empire's victims and its opponents.
Decolonisation itself remains an evergreen favourite for historians, including Cambridge veteran Ronald Hyam with his near-encyclopaedic Britain's Declining Empire (Cambridge, 17.99) and Piers Brendon with a more impressionistic popular overview, The Decline and Fall of the British Empire (Cape, 25) .
If predictions of a lasting "American empire" may now seem less confident, the debate over it is far from exhausted. Important new interventions range from day-by-day reportage to essays in grand theory. Maybe the finest instance of the former this year was Rajiv Chandrasekaran's despatches from occupied Baghdad, Imperial Life in the Emerald City (Bloomsbury, 12.99). As for the latter, especially engaging has been yet another attempt to draw together the "lessons" of empires past: Herfried Munkler's Empires (Polity, 18.99). What makes Munkler's effort intriguingly different is that he doesn't just talk about America, but offers fascinating thoughts on the European Union as, at least potentially, a kind of empire too.Reuse content