Every April, New York’s proud Scottish-Americans celebrate their heritage with the Tartan Day Parade, processing up Sixth Avenue in a sea of kilts, to the noble blare of the bagpipes. If you are thinking of attending the festivities next year, however, you might want to keep quiet about having read “The Invention of Scotland” (Yale University Press, 304 pages, $30), a punchy new book by the late historian Hugh Trevor-Roper. For as Trevor-Roper points out with ill-concealed glee, tartan and kilt, those universal badges of Scottishness, are about as authentic as Disneyland. Until the 18th century, no one north of the Tweed had ever seen a kilt; nor did the clans, as legend has it, distinguish themselves by the pattern of their tartans, until they were taught to do so by an enterprising clothing manufacturer. The Scottish costume is, Trevor-Roper shows, simply the latest example of an ancient national habit: the forging of tradition.

The word forging, however, can be taken in two senses. There is the fraudulence of the forger of documents, but there is also the honest labor of the forger of steel; and while Trevor-Roper focuses on the first of these meanings, he does not exclude the second. He recognizes that the invention of Scottish history was a creative act, which helped Scotland to emerge as a cohesive and peaceful modern nation. “The creation, and re-creation, of myth requires a continuous capacity for invention,” he writes, “and its formalization can be seen as a ritual adjustment, a formal accommodation of barbarism to civility.” Because Trevor-Roper was a leading historian of Nazi Germany, he is especially appreciative of the benign forms that Scottish mythmaking took: “In Germany, the ancient barbarisms of the race were revived in all their savagery. … Ritualization would have been better.”

“The Invention of Scotland” was left unfinished when Trevor-Roper died in 2003, but it does not read like a collection of fragments. In fact, these eight chapters, based on essays and lectures that the historian wrote in the 1970s, fall neatly into three related sections, each dealing with an important episode in the “forging” of Scottish history. The first, titled “The Political Myth,” explores the way Scottish scholars of the 16th century — above all, the great Renaissance man George Buchanan — advanced a grossly erroneous version of Scotland’s history, the better to serve their contemporary political purposes. The second, “The Literary Myth,” is a feat of documentary detective work, in which Trevor-Roper untangles one of the most famous frauds in literary history: the invention of the ancient bard Ossian by James Macpherson. Finally, and most playfully, Trevor-Roper turns to “The Sartorial Myth,” offering the surprising truth about how and why the kilt and tartan became Scottish institutions.

The Scots’ continual resort to mythmaking, from medieval times down to the 19th century, seems to Trevor-Roper to demonstrate an essential truth about the Celtic mind, as opposed to the Anglo-Saxon. Drawing on an old but resilient stereotype, he contrasts English prosiness with Celtic imagination. Yes, he admits, the English “have created one of the great literatures of the world. Yet, have they a single myth that they can call their own?” Surely it is no accident that all the great mythic heroes of the British Isles, from Cymbeline to King Arthur, were invented by the Celtic peoples — the Welsh, Scots, and Irish — who inhabited the land before the Anglo-Saxon invasion.

Much of what has passed for the truth about Scottish history, Trevor-Roper suggests, is actually the product of this same mythopoetic impulse. Consider the case of Hector Boece, a 15th-century scholar and humanist from Dundee who wrote a hugely influential “History of the Scots.” Boece was not content with the truth about the Scots — that they were an Irish people who migrated to western Scotland in the fifth century C.E. (“Scotus,” in Latin, originally meant “Irish.”) Jealous of the alleged antiquity of the English, who traced their descent to Aeneas and the Trojan Wars, Boece elaborated a rival myth, according to which the Scots were descended from an ancient Greek hero, Gaythelos, and his wife Scota, an Egyptian princess who was the daughter of the biblical pharaoh.

Because Boece alleged that their descendants — who took the names Gael and Scot in their memory — arrived in Scotland in the fourth century B.C.E., he was faced with a 900-year gap in the historical record. He filled it by inventing 40 kings, whom he not only named but provided with what Trevor-Roper calls “elaborate and detailed biographies.” Among them were many wicked monarchs, “a set of human monsters, vicious, violent, and frightening” — such as Lugtacus, who “repeatedly raped his aunts, his daughters, his sisters and their daughters.” As befit a moralistic historian, Boece showed these evil kings receiving due punishment, as their suffering subjects deposed and executed them.

Little did he suspect that, in inventing these fables, he was handing powerful ammunition to the real-life rebels who arose during the troubled reign of Mary Queen of Scots. Among these was George Buchanan, whose career and personality Trevor-Roper discusses in detail. Toward the end of his life, Buchanan — “by universal consent the greatest Latin writer, whether in prose or verse, in sixteenth-century Europe” — emerged as one of the chief apologists for the noble conspirators who deposed Mary in 1567. In order to convince the world, and especially Queen Elizabeth of England, that the nobles had acted legally, Buchanan wrote a pamphlet arguing that the Scottish constitution had always allowed for the removal of kings. As proof, he cited Boece’s made-up tyrants, whose fictional punishments were now used as precedent for the deposition of Mary.

In this way, the myths about Scottish history invented by Hector Boece turned into a genuine historical force, making them immune to debunking. Trevor-Roper shows that when another historian, the Welshman Humphrey Lluyd, published a work proving that Boece’s 40 kings had never existed — thus destroying the historical basis for Buchanan’s political theory — Buchanan responded by launching a “pathological” personal attack on Lluyd. Buchanan must have known that his theory about the Scottish constitution was disproved, yet he refused to acknowledge Lluyd’s evidence. Trevor-Roper issues what is, for a historian, the most damning of verdicts: “Buchanan knew that Boece was historically worthless and could not be safely followed or openly cited; but since he depended on him for his essential thesis, he secretly used his work … The old fabrications were presented to the learned world in a more acceptable form.” Protected by Buchanan’s authority, the “forty kings” became an unchallengeable article of faith among the Scots for another two centuries, even as the English were discarding their old myths and embracing a scientific approach to history.

The next episode in Trevor-Roper’s study, the invention of Ossian, did not have such important historical consequences. But it was deeply telling about the enduring Scottish need to believe in the antiquity and cultural superiority of their race. As Trevor-Roper writes, “when a society renounces politics, it can find other ways of expressing its identity,” and after the 1707 Union of Scotland and England, Scottish nationalism took on cultural and literary expression. In 1761, when an obscure schoolmaster named James Macpherson announced that he had discovered and translated an ancient Gaelic epic called “Fingal,” by a warrior-bard named Ossian, the literati of Edinburgh reacted with explosive enthusiasm. Ossian was hailed as a Scottish Homer, proof that the ancient civilization of the Scots was equal in genius to that of the Greeks.

Even better, as Trevor-Roper notes, “Fingal” conspicuously lacked all the features that the 18th century was beginning to find uncouth in the Iliad: “Here were no human sacrifices, no petty thieving, no princesses washing knickers in the river. Indeed there was nothing common, or even concrete, at all. All was high-minded humanity, sensibility, chivalry.” So perfectly did Ossian reflect the taste of the age that his epic — which today, as Trevor-Roper says, seems “totally unreadable” — numbered Goethe, Napoleon, and Thomas Jefferson among its devotees.

Yet right from the start, there were critics — mainly English — who smelled a rat. How did Macpherson, who barely knew Gaelic, manage to find and translate a 1,500-year-old poem? Why did so many phrases from “Fingal” seem to echo the Bible, Shakespeare, and Milton? Above all, why could Macpherson not produce the original manuscript of the poem, despite numerous requests? Samuel Johnson concluded that the works of Ossian

never existed in any other form than that which we have seen. The editor, or author, never could show the original; nor can it be shown by any others. To revenge reasonable incredulity by refusing evidence is a degree of insolence with which the world is not yet acquainted, and stubborn audacity is the last refuge of guilt.

Yet even once English opinion unanimously rejected Ossian as a fraud, the Scots continued to have faith. It was easier to believe Macpherson’s fantastically complex lies, which Trevor-Roper has great fun exposing, than to accept that the Scottish Homer was an impostor.

After all this, it is hardly a surprise to learn that the kilt and tartan, too, are not quite the Scottish traditions that they seem. Sad to say, the kilt was invented by an Englishman, Thomas Rawlinson, who came to Scotland in the 1720s to manage an ironworks in the Highlands. Rawlinson observed that while the actual native costume of the Highlanders — the long belted cloak called the plaid — might have been suitable for rambling over hills and bogs, it was “a cumbrous, inconvenient habit” for men working at a furnace. So he hired the tailor of the local army regiment to make something more “handy and convenient for his workmen” by “separating the skirt from the plaid and converting into a distinct garment” — the kilt. This symbol of Highland tradition, as Trevor-Roper notes, was “bestowed … on the Highlanders, not in order to preserve their traditional way of life, but to ease its transformation: to bring them off the heath and into the factory.” As with so many of the tales Trevor-Roper has to tell, the truth may not be as romantic as the legend, but its irony makes it no less compelling.

akirsch@nysun.com