Many of the best biographies this year came at their subjects from a slant. Matthew Hollis, for instance, confined himself to the last four years of the poet Edward Thomas's life. Now All Roads Lead to France (Faber, £20) follows Thomas as he packs up his kit bag and heads off to Arras, taking his newly expressed poetical gift with him, having spent the previous decade as a jobbing prose hack. Hollis's great achievement is to use the odd shape of Thomas's verse life as a way to explore the state of British poetry on the eve of the Great War, poised between Georgian lyricism and stark modernism. He triumphantly demonstrates how, far from being a baggy or moribund genre, biography can be a sharp tool of literary criticism.

Ann Wroe's Orpheus: The Song of Life (Jonathan Cape, £17.99), meanwhile, pursues its mythological subject through every cultural layer imaginable: art, legend, poetry, film and music, from the 6th century BC until now. Wroe is one of the most interesting biographers writing today, always refusing the easy and the obvious in favour of the fugitive and the frankly strange. Read Orpheus for its erudition, its great leaps and hops of imagination and, above all, for Wroe's singing prose.

No less moving is Caroline Moorehead's A Train in Winter (Chatto, £20). Moorehead has dug through the French archives to uncover the story of 231 women, all members of the Resistance, who were sent to Auschwitz in 1943. One by one the women perish, falling prey to cold, hunger and sustained Nazi brutality. Only 49 get out alive. Moorehead tells her appalling story in a measured prose that sets off pefectly the reader's growing sense of wonder that such heroism is possible.

Another group biography that did a splendid job of telling an unknown or unlikely story was Maya Jasanoff's Liberty's Exiles (Harper Press, £30). In it she reminds us that no fewer than 60,000 Americans decided to stay loyal to the British crown during the revolution. When the redcoats finally left in 1783, these brave souls had no choice but to pack up too. This is the best kind of revisionist scholarship, giving us new ways of thinking about a subject that we thought we knew backwards.

Another unlikely biographical subject under the spotlight this year was Simon Phillips Norton, the mathematical prodigy who had dropped out of his academic career by the age of 30 and taken to studying country bus timetables instead. Alexander Masters tells his story fizzingly in The Genius in My Basement (Fourth Estate, £16.99), the title a reference to the fact that Norton lurks slummily in the nether regions of Masters's Cambridge lodgings. Masters had a fantastic hit with his first book, Stuart: A Life Backwards, which meant he faced the "difficult second album" phenomenon with a vengeance. In fact, he's risen to the challenge brilliantly, producing a book that is not only a kind, funny account of a stunningly odd man, but into the bargain educates the reader about higher maths.

Just to prove that classic cradle-to-grave biography still has a place in our fractured reading landscape, along comes Claire Tomalin's wonderful life of Charles Dickens (Penguin, £30). Where Tomalin scores over previous  male  biographers is in the acute emotional intelligence she brings to her telling of Dickens's contradictory life. Here was a man who wrote endlessly about the pleasures of home and hearth, yet who in middle age went out of his way to break up his own household. Twenty years ago Tomalin wrote an extraordinarily good book about Nellie Ternan, the young actress whom Dickens left his wife for in ways so humiliating that even now it hurts to read about them. This time around, by taking a larger canvas, Tomalin is able to explore just how Dickens's cruel, wayward middle age had its roots in the appalling mess of his childhood.

Fiona MacCarthy's The Last Pre-Raphaelite: Edward Burne-Jones and the Victorian Imagination (Faber, £25) is another fine example of a biography written along classic lines. In it MacCarthy brings all her scholarship, eloquence and deep sympathy to bear on the artist whose work came to typify the strange dreamworld of late 19th-century painting. Biographies of artists have been getting skimpier on their illustrations in recent years (it's a cost thing). But Faber does MacCarthy proud, and the result is one of the handsomest  as well as most compelling  biographies you will read this year.

 Which biography would you give this Christmas?

We often think of Edward Thomas (1878-1917) as a pastoral poet of place and belonging, but his real subjects were disconnection, discrepancy and unsettledness. His poems are thronged with ghosts, dark doubles, and "unfathomable deep" forests, and his landscapes are brittle surfaces, prone to sudden collapse. FR Leavis got it right when he described Thomas's poetry as working at "the edge of consciousness". Even his most anthologised poems  "Adlestrop" or "At the Team's Head-Brass"  reach towards knowledge which is ungraspable or somehow lost.

Matthew Hollis's excellent account of Thomas's last years gives us a context for these aspects of his verse. Hollis's Thomas is a man shot through with depression and doubt, a man  in his own words  "plagued with work, burning my candle at 3 ends", racked with self-loathing for not having the courage to kill himself, unhappy in (though never unfaithful to) his marriage, vile (though never violent) towards his ever-loving wife Helen. Walking and nature offered him temporary consolations, but until he met Robert Frost in 1913 Thomas seemed certain never to write poetry and very likely to commit suicide. The friendship between them, and Thomas's decision to fight in France (he was killed on the first day of the battle of Arras), are at the heart of this book.

Hollis opens with an evocation of the London poetry scene of a century ago. It was a rambunctious world: here is Ezra Pound judo-throwing Frost to the floor of a restaurant ("I wasn't ready for him at all," protested a disgruntled Frost afterwards); TE Hulme hanging Wyndham Lewis upside-down by his trouser turn-ups from the railings on Great Ormond Street (credit to the strength not only of Hulme's upper body but also of Lewis's trousers); back-stabbing and back-scratching behind the shield of review-anonymity. These were the emergent years of literary modernism, and the excitement of old clashing with new is well summoned by Hollis: the Georgians lavishing their glossy poetic "caresses" on the world's phenomena, Pound blasting away at tradition, and all the while the war bearing down on the city and its unwitting poets.

Into this world, from different directions, moved Frost and Thomas. Frost arrived on a boat from America, hoping to make his name as a poet in England, having failed to do so in his home country. Thomas, famously, came late to poetry, or rather poetry came late to him: in his lifetime he was best known as one of London's most powerful critics, notorious for the sharpness of his pen. Hollis restores this largely forgotten aspect of Thomas's career: a reviewer so influential that he was said to hold "the Keys to The Paradise of English Poetry", who was known as "the poisoner" for the toxicity of his negative notices, who was fearless in his judgments (he scorned Yeats's Celtic revivalist verse for "moving about in a world where perfect dreams are as cheap as evening papers") and for whom criticism was a moral act which had to be carried out in "a language not to be betrayed".

But then, as now, it was near-impossible to make a living working only as a critic. Hollis records the brutal grind and its dismal effects on Thomas's morale. Lashed to his desk, financially committed to writing hundreds of thousands of words a year (biographies, histories, critical studies, travel books as well as the endless reviews), Thomas sank further into depression. By 1912 his mind was, in Hollis's sharp phrase, "bitter and furtive", he was insomniac and volatile, often lashing out at his wife.

Then he met Frost, and by the spring of 1914 the two men were so close that they were considering moving together to America. Frost was the only man who  with his New England bluffness  could bounce Thomas out of his self-pity. Much of their time together was spent "talks-walking" (Frost's verb) around the village of Dymock in Gloucestershire, where for a few years a group of poets gathered to wander, think and drink. Even as the plains of Belgium were being scorched and a "human wall of refugees" was being driven ahead of the advancing Germans, the Dymock poets were still living out their eclogue, with conversation the labour and poetry the harvest.

The war saved Thomas before it killed him. It gave him purpose and, obliquely, it gave him poetry. "I am slowly growing into a conscious Englishman," Thomas wrote in September 1914, and his first poem came two months later. In little more than two years  under Frost's careful counsel  Thomas wrote a lifetime's poetry. Even through these months, though, Thomas was still accepting such "filthy jobs" as "a book on the Duke of Marlborough to be done in haste" (it took him 10 weeks: six to research it and four to write it, at up to 3,000 words a day).

Thomas recognised the distinctively industrialised nature of the first world war: it was a vast machine designed, as he put it, "to turn young men to dung". But he sought out action anyway, ending up commissioned as a second lieutenant in an artillery battery. He ceased writing poetry shortly before he embarked for France. Within 10 weeks of arriving on the Western Front he was dead, killed gently by the shockwave of a passing shell which stopped his heart and threw him to the ground, but which left his clay pipe unbroken and the pages of his pocket-loop notebook creased into curious ripple patterns.

Hollis  like Thomas, a poet, an editor and now a biographer  tells all of this very well, his account beautifully structured by place, year and season. He has chosen not to set himself up in stylistic competition with Thomas; his narrative is calm and discreet, his tone witty and scholarly. His sympathy for Thomas and his admiration for the poetry are clear, but he is unsentimentally candid about his subject's troubles and solipsism.

In 1985 Ted Hughes described Thomas as "the father of us all". Hughes was speaking as a poet to other poets, but his comment is more widely true. So much about Thomas's life and work now seems to have anticipated contemporary anxieties: his irreconcilable impulses to travel and to dwell, his difficulty at knowing what to call "home", his environmentalist's interest in bio-regionalism, and his exile's sense that "place" might be best understood as the sum total of the locations that have been left behind. Hollis's fine book helps us to understand how much more there is to Thomas than willow-herb and meadowsweet and haycocks dry.

Robert Macfarlane's The Wild Places is published by Granta.