Around the 1990s, the historical Celts endured something of an identity crisis. First in academic articles, then in popular books, and eventually in newspaper headlines, people started loudly declaring that ‘Celts’ did not really exist. Not all the scholarly ideas were new, but the mood certainly was: the general consensus that you could use the word Celtic to conjure up a relatively coherent historical people was called into question. The discipline of Celtic Studies grew anxious and self-critical: I have heard, from senior colleagues, accounts of students begging them to teach what could be said about the Celts, rather than the things that couldn’t. Modern ‘Celts’, in particular, started to gain scare quotes: these identities, it appeared, were recent inventions grafted onto historical abstractions, a collage of disparate symbols from the pre-Roman past, stuck together with imagination, enthusiasm, and academic linguistics. Ian Stewart’s The Celts: A Modern History broadly agrees with these conclusions. But rather than seeing this as a reason to abandon the Celts, Stewart builds on recent scholarship to make a compelling case for the significance of modern Celticism, in all its paradoxical glory.

This is a big, ambitious, erudite book. After a crash course on academic trends, and on ancient evidence for the Celts, Stewart begins in the early modern period, with the scholarly recovery and reconstruction of Celtic knowledge. This recovery was required after the near-total disappearance of Celtic ideas in medieval Europe, but Stewart avoids portraying the era as one of dry, disinterested scholarship. As he writes, nation and race ‘are kept firmly in view throughout’, and he shows that debates about Celtic history and linguistics frequently descended into squabbles over ‘prestigious ancestors whose legacy was up for grabs’. Repeatedly, we come across authors who just so happen to discover that their own local dialect was the original tongue of all Europe.

For the uninitiated, the prominence of German claims to Celticity might come as a surprise: Celtic and Germanic concepts were not definitively separated until the late 18th century, and the apparent incongruence of modern German-speakers identifying as Celts might make their scholarship seem faintly ridiculous. But alongside a record of intellectual missteps and prejudices, Stewart demonstrates the real and lasting linguistic discoveries made in this era, not least the proofs of Celtic linguistic relatedness published by the Welsh Edward Lhwyd in 1707, which had already been ‘speculatively’ suggested by the German G.W. Leibniz. Readers expecting dramatic tales of neo-druids and national struggles will, I hope, not turn away from extended sections on (for example) the significance of the phonological distinction between P-Celtic and Q-Celtic: part of the cleverness of Stewart’s book is that he manages to combine a full account of the weirder and wilder Celtic theories with evidence that, in among the eccentricities, genuine scholarly advances were taking place.

On the subject of scholarly advances, one of the many innovative aspects of Stewart’s grand narrative is his focus on James Cowles Prichard (1786-1848), an Anglo-Welsh ethnologist who emerges as one of the pioneers of placing Celtic languages in the Indo-European family. Prichard is shown to have profoundly influenced the continental linguists who often get most of the credit. He also, however, inaugurates a section of Stewart’s book in which the concept of race becomes central to the expression of Celtic identity. Here, for instance, we find the Scottish phrenologist George Combe (1788-1858) predicting, by lucky accident, the emergence of a second Napoleon in 19th-century France, based on his belief that ‘the small Celtic brain of the French’ was ‘vulnerable to demagoguery’.

A chapter on race and the ‘Irish Question’ surveys a large and contentious body of evidence on the role of anti-Celtic racism in Britain’s treatment of Ireland, concluding that any racialised interpretation must always be balanced with other specific factors. And a brilliant consideration of the ‘Land Question’ across the British Celtic fringe shows that racial rhetoric was just as important in attempts to unify opposition to ‘Saxon’ landlordism as it was in English denigration of ‘Celtic’ tenants. This duality continues to be important in the book’s final section, which focuses on the dawn of organised pan-Celticism around the turn of the 20th century. Here Celtic connectivity was asserted on combined racial and linguistic grounds: it could be mobilised on behalf of both nationalist radicalism and quiescent Unionism, and conferred an ongoing racial tinge to the self-consciously anti-colonial and left-leaning Celtic activism that developed as the century wore on. Hitler, it emerges, might have thought Jesus was a Celt, and the Nazis used Celtic Studies for their own ends; but that didn’t stop later left-identified pan-Celts from asserting that Celtic society was ‘always socialist’.

In a book that covers this much ground, it is always possible to think of other routes that might have been taken. Stewart is a historian of ideas, not a literary critic: you could imagine a narrative in which poetry, novels, and aesthetics play a bigger role. Similarly, you could write a book in which material written in, rather than about, the various Celtic languages was more central. But this latter point seems churlish when Stewart – whose multilingual focus on English, French, and German is unprecedented – is also able to cite more primary and secondary Celtic-language sources (predominantly in Welsh) than is usual for scholars outside Celtic Studies. Pan-Celticism itself was a movement so uncomfortably aware of its dependence on English that there were attempts to make Esperanto its alternative lingua franca.

From the fashionable melancholy Celticists of the 18th century to the scholarly sceptics of the 20th, people have long predicted the imminent disappearance of the Celts. But as Stewart’s book shows, like King Arthur returning from Afallon, the Celts are always coming back.

• The Celts: A Modern History
  Ian Stewart
  Princeton University Press, 576pp, £35
  Buy from bookshop.org (affiliate link)
   

Rhys Kaminski-Jones is a Research Fellow at the University of Wales Centre for Advanced Welsh and Celtic Studies and the author of Welsh Revivalism in Imperial Britain (Boydell & Brewer, 2025).