Rosemary Sutcliff crafted her historical novel The Eagle of the Ninth from two starting points: a small bronze eagle found at Silchester, which is now in Reading Museum; and the unknown fate of the Roman Ninth Legion, which, based in York, had apparently vanished from the historical record in the early years of the 2nd century. Written, as always, “for children aged 8 to 88” The Eagle of the Ninth is about a young centurion, Marcus Aquila, who takes up his first command on the edges of the Roman empire in south-west Britain. Severely injured during a fight with local warriors who have been inflamed by a travelling druid, he has to give up his military career. However, he  hears rumours of sightings of  the standard of his father’s lost legion – the eagle of the ninth –  north of Hadrian’s wall. He realises that if he can find it, he will restore the honour of his disgraced father and the legion he commanded.

Last year, at the time of the release of the film The Eagle, Charlotte Higgins, chief arts writer of The Guardian newspaper, wrote a long, affectionate article about her children’s favourite.

… In an interview in 1992, the year she died, she said: “I don’t write for adults, I don’t write for children. I don’t write for the outside world at all. Basically, I write for some small, inquiring thing in myself.” I have read The Eagle of the Ninth dozens of times; and as the reading self changes, so does the book. When I last read the story, it was the quality of the prose that delighted, the rightness with which Sutcliff gives life to physical sensation. A battle fought through the grey drizzle of a west country dawn is illuminated by “firebrands that gilded the falling mizzle and flashed on the blade of sword and heron-tufted war spear”. Perfect, too, is a set-piece in which Marcus, on a stiflingly hot day, puts his British hunting companion’s chariot-team through their paces. “The forest verge spun by, the fern streaked away between flying hooves and whirling wheels . . . Then, on a word from Cradoc, he was backed on the reins, harder, bringing the team to a rearing halt, drawn back in full gallop on to their haunches. The wind of his going died, and the heavy heat closed round him again. It was very still, and the shimmering, sunlit scene seemed to pulse on his sight.” Sutcliff, tellingly, has those black chariot ponies – “these lovely, fiery little creatures” – descended from the royal stables of the Iceni, the tribe who had almost cast Rome out of Britain. It is a delicately inserted hint of danger to come.

She also conveys the heavy, gruelling thud of physical pain so well. I was struck afresh when last rereading The Eagle of the Ninth how – without the tension letting up for a second – she allows a good chunk of the centre of the book to be occupied by the sensations and consequences of Marcus’s injury, before the true adventure, the quest to find the eagle, can begin. Physical pain and incapacity were trials with which Sutcliff herself was horribly familiar: aged two, she contracted Still’s disease, a form of arthritis, and for most of her life she used a wheelchair. That and an itinerant childhood as the daughter of a naval officer, meant when young she was educated by her mother, and did not learn to read until she was nine. But the learning she got at her mother’s knee was surely the perfect training for a storyteller: she was told stories from the Norse and Celtic legends, fairytales, Icelandic sagas. There was Malory, too, and the Mabinogion, “which has been part of my life for as long as I can remember”, she told an interviewer in 1986. Her first attempts at writing were retellings of her mother’s tales.

Marcus then, invalided out of the army, joins his uncle Aquila, a retired army officer, at his house at Calleva. Here he “comes face to face with the wreckage of everything he knew and cared about”. He is lonely, in pain and homesick, enduring “the wind and rain and wet leaves of exile”. Gradually, though, he forms the relationships – not with soldierly young Romans, but with a slave, a wolf cub and a young British girl – that will rescue him from his solipsism. All four are deracinated, solitary creatures. Esca, a Briton of the Brigantes tribe, has lost his family to Roman slaughter as well as his freedom. Cub has been plucked from the lair of his she-wolf mother, killed by hunters. The proudly British Cottia has been sent to live with her aunt and uncle, whose comically over-eager adoption of a Roman lifestyle she despises.

Sutcliff … is greatly interested in questions of identity. What does it mean to be British? Where is home? Can a slave and a free man be friends? The Eagle of the Ninth was published in 1954 and speaks deeply of its time. The relationship Sutcliff sketches between Marcus and his slave Esca now seems troubling … Sutcliff‘s Esca, for a man whose entire family has been wiped out by Marcus’s fellow soldiers, seems more than a shade too unquestioning in his loyalty to Marcus, even given that Marcus all but saved him from death in the gladiatorial arena. A scene in which Cub is offered his freedom – but then comes trotting back home, humbly offering his muzzle to his master – is uncomfortably echoed by a parallel scene in which Marcus offers Esca his manumission papers, only for the Briton, just like the potentially savage wolf cub, to declare his continued devotion to the Roman. Sutcliff‘s implicit view – that friendship necessarily trumps tribal enmity – has been rather severely shaken by a half-century of post-colonial bloodshed.

For all that, The Eagle of the Ninth is not only a rollicking good adventure, but also a touching and true story about friendship, love and loyalty. Sutcliff could write a good battle, and her stories burst with soldiers and fighting men; but these are not brutal military automata. Marcus is the kind of man who notices a pot-bound rose bush growing out of an old wine jar outside his military quarters. Sutcliff attended art college from the age of 14, and specialised in miniature painting. “Fortunately, I have got a very good memory,” she once explained. “And it’s a visual memory: I was taught how to look at things. And I’ve found this really useful because I know just how things will look . . . how the colour of sunlight gleaming off a sword will change, depending on whether it’s a warm sky or not.” A miniaturist’s visual skill, then, but deployed on a huge imaginative canvas: desperate moorland chases on horseback; a fort subject to a vicious attack; strange and wild native rituals practised by night.

• Full article here in The Guardian