There is a statue of Lord Castlereagh (1769–1822) in Westminster Abbey, but the inscription on his grave nearby has, with perfect melancholy symbolism, worn away. With the exception of the Irish, who forget nothing, Castlereagh is usually remembered, if at all, only for fighting a duel with a cabinet colleague and for committing suicide with a penknife, the sole British foreign secretary to have done so, by that or any other method.

Mainstream historians who prefer to run no risks might add that Castlereagh was a wicked reactionary, author of the policies that generated the insults that have kept his name alive in literature, if nowhere else. Byron labeled him an “intellectual eunuch”—a sneer made all the more cutting by his target’s childlessness—and rejoiced at his suicide: “Here lie the bones of Castlereagh/ Stop, traveler, and piss.”

Shelley, not to be out-Michael Moored, had this to say in the aftermath of the bloody suppression of calls for parliamentary reform:

I met Murder on the way – He had a mask like Castlereagh –
Very smooth he looked, yet grim;
Seven blood-hounds followed him:
All were fat; and well they might
Be in admirable plight,
For one by one, and two by two,
He tossed them human hearts to chew
Which from his wide cloak he drew.

Henry Kissinger, however, is something of a fan.

Castlereagh, with Metternich, was the subject of Kissinger’s first book, A World Restored: Metternich, Castlereagh, and the Problems of Peace 1812–1822. It is long out of print, but at least it gave him the billing he deserved. That’s unusual: Looking through the extensive bibliography at the end of John Bew’s fine new life of Castlereagh, it’s striking to see how few books published in the last century include his subject’s name in their titles. The title of one of those that do—C. J. Bartlett’s Lord Castlereagh: The Rediscovery of a Statesman (1969)is itself an indication of fame that has passed into shadow.

Castlereagh was one of the architects of Britain’s victory over Napoleon and, at the Congress of Vienna and thereafter, a creator of the system that helped shape that continent for a century—the Concert of Europe. He was simultaneously the Foreign Secretary and the Leader of the House of Commons for a decade. Dublin-born, he played a prominent role in the suppression of the Irish rebellion of 1798. Two years after that, he was instrumental in forging a formal union between Great Britain and his homeland. Sic transit gloria and all that, but his current obscurity seems overdone. Shelley, the author of “Ozymandias,” might have approved, but Mr. Bew evidently does not.

His book is designed “to challenge [the] image of Castlereagh as an unthinking reactionary,” and also, I suspect, to restore this forgotten giant to the prominence that he deserves—for good or bad—in Britons’ understanding of their own past. Bew succeeds on the first count and, aided by his formidable storytelling skills, deserves to do no less on the second. Intricate descriptions of Castlereagh’s political and diplomatic maneuverings are inevitable, and they come with their longueurs. But these are more than offset by a sensitive, sympathetic and lively depiction of the man as well as the politician, and of a family that included the Bizarro Castlereagh: his half-brother, “Fighting Charlie,” a proto-Flashman in the George MacDonald Fraser style, whose louche exploits act as a jangling, ribald refrain to his older sibling’s infinitely more stately waltz.

Bew has an eye for the entertaining detail, and he depicts a time and a place impossibly remote and startlingly close. Popular resentment over “tales of ostentation and obscene wealth” that emerged from the seemingly endless series of international conclaves reminds us that the distance from Vienna and Aix-La-Chapelle to Turtle Bay, Davos, and Brussels is not so great after all.

And then there are this book’s more profound contemporary resonances. Europe is now again in disarray, a global revolutionary movement—this time Islamic (how the philosophes would have despaired)—is on the march. New powers are asserting themselves with little respect for the rules of the post-1945 game. Castlereagh would have recognized the picture, and, with his Hobbesian view of humanity, would not have been terribly surprised. As he would have understood, the United States, Britain’s successor as top dog in the pound, has to work out a response, a process that must first involve deciding what foreign policy is for.

About that, Castlereagh had few doubts by 1814. After the expense, danger, and disruption of the Napoleonic wars, the national interest defined (as it always should be—coldly, clinically, and with practical amorality) lay in the maintenance of a peaceful Europe that left Britain free from danger and its trade from disruption. Sharper than the treaty makers at Versailles a century later and too coolly rational to be interested in revenge, he blocked plans to impose a harsh, inherently destabilizing settlement on the defeated France. What he wanted—and what he got—was the creation of a continental balance in which no one power predominated. If that meant going along with a despot or two, so be it. Stability was its own reward. Extreme reaction was potentially as unsettling as “political experiment and popular delirium,” and no less to be discouraged. Attempts by Russia’s increasingly bizarre Czar to recruit Britain into a monarchical Holy Alliance intended to impose a cross-and-scepter anticipation of the Brezhnev doctrine on Europe was rejected. “Mysticism and nonsense” said Castlereagh, as, indeed, it was.

Those are not the words of an unreconstructed reactionary. On the contrary, Castlereagh was, Bew proves, a man of the Enlightenment, but without illusion. He had little time for the stupidities of the ancien régime, but he also witnessed revolutionary France (“that pile of ruins”) first hand. Chaos, he saw, was rarely a friend of liberty, progress, or prosperity. He would have cast a cold eye over the Arab Spring. Change, he accepted, could be for the good, but the best chance of it to work out that way would be for it to be incremental, gradual, and cautious—sometimes, as in the case of his careful support for the abolition of slavery, excruciatingly so. With Castlereagh, calculation and principle walked hand-in-hand.

Thus, the formal absorption of Ireland into a greater (comfortably Protestant) United Kingdom would, he thought, smooth the way to the Catholic emancipation that Castlereagh (to use American terminology, a Scotch-Irish Presbyterian) regarded both as a worthy objective and an essential element in the anchoring of John Bull’s other island. George III disagreed. Perhaps losing America was not enough. Catholic emancipation was delayed for another three decades, further poisoning a well that Castlereagh had already done his bit to pollute.

For when Ireland rose in rebellion in early 1798, Castlereagh went along with, and then presided over, a ferocious response which was shocking even then, and for which he bears more responsibility than Bew appears willing to admit. Cornwallis (yes, that Cornwallis) arrived in June that year to take charge, and quickly grasped that the extreme brutality was self-defeating and adopted a more moderate course. Castlereagh again went along, impressing Cornwallis with his loyalty to the new line. As Bew demonstrates, Castlereagh could be the chilliest of apparatchiks, but he was no sadist. The excesses had been distasteful. Worse, they were counterproductive, an unforgivable flaw to this supremely pragmatic man.

He himself was never to be forgiven for them, either in Ireland or by a growing army of liberal critics outraged first by Castle-reagh’s behavior in Ireland, and then by his support for a Europe in which Habsburg, Hohenzollern, Bourbon, and Romanov were free to dash both the hopes of the Enlightenment and the dreams of smaller nations. The abuse thrown at him would have been all too recognizable to George H. W. Bush (not to speak of his son), a lesser master of Realpolitik, but a skilled player of the diplomatic game nonetheless, whose resemblances to Castlereagh include an inarticulacy that was a gift to his opponents, mercilessly used. Castlereagh’s heavy-handed opposition to political reform at home (with its echo of earlier Irish horrors) and acid reluctance to lend even verbal assistance to liberal crusades abroad, such as Greece’s struggle against Ottoman rule, only sharpened his critics’ sense that their bogeyman was on the wrong side of history. Similar sentiments put him on the wrong side of historians too. And they wrote him out of the script.

To mention George H. W. Bush is to remember that pragmatism taken too far can be the opposite. Stasis is not always stability, sticking to the rules is not always the best policy, and precedent is not always a good substitute for imagination. It’s easy to imagine that Castlereagh, iciest of statesmen, would have abandoned the Shia of Southern Iran, and, for that matter, turned up in Kiev to advise Ukrainians to stay within their crumbling Soviet home. But to argue, as the caricature would have it, that, had not overwork and stress—there are other, more exotic explanations—driven him to suicide, Castlereagh would undoubtedly have encouraged the Concert of Europe to keep playing an unchanged tune in rapidly changing times is to underestimate the subtlety and cleverness of a man, who for all his failings, has been sold short for too long.

After this book, there’s no excuse for that.