Versions of the legendary Danish king, Hrothgar, pop up in many northern European folk tales and oral histories. Most notably, of course, he is the builder of Heorot, the vast mead hall that, in Beowulf, is attacked by the monstrous Grendel. He appears in sagas from different communities and at different times, where for the most part he is seen as the wise old head who has encountered many conflicts and resolved them with strength and guile and the support of his loyal followers, for he is almost always depicted as a generous and big-hearted leader.

At around the time of the derivation of his story – consensus places him as a fictional contemporary of (the almost certainly real) King Eadglis – that is to say, the mid 6th century, the Danes and their neighbours had not yet begun to regard the eastern coast of Britain as a target for raiding and expansion. And they wouldn’t for another two hundred years, but tales of Hrothgar’s deeds were tenacious in the retelling and it is no surprise that in some instances he can be found as a ruler in Northumbria and, as I discovered, in a remote corner of Cambridgeshire.

Today, the southern stretch of the English east coast is a very different landscape to that which the Vikings would have powered toward. Then, the distinction between sea and land was a blurred confection of swamp and marsh and fen, a truly immense wetland puzzle. Scattered communities had always exploited the area for fishing, of course, but it was the Romans who made the first concerted effort to control the environment. They built the Fen Causeway, a 24 mile road between Denver – just south of Downham Market – and Peterborough. Primarily, they were interested in transport for goods (livestock and leather, fish and salt, oysters and reeds) and although they attempted drainage, the dykes they built were essentially canals for the swift movement of flat-bottomed barges rather than any serious attempt at claiming new land. Across the area, population centres developed on the groups and chains of small hills and rises which peppered the soggy lowlands. Connected by the wooden causeways between these upland strips, towns and villages grew up closer to each other than might naturally occur elsewhere. So it is around Burwell, Exning, Reach, Swaffham Prior, all fen edge villages, all within a stone’s throw of one another.

Reach, or ‘Reche’, wears its connection to the past most distinctively. It is here that the Devil’s Dyke begins, a significant earthwork structure, best (if rather unhelpfully) viewed from the air, as all these things tend to be, a great scar that shoots arrow straight South East, to the village of Wood Ditton, seven miles away. At Reach, it takes the form of a concave trough, as if years ago a meteor hit and just carried on ploughing through the fields and out of sight, but which has long since been grassed over. Further along it boasts impressive ten metre high back-filled walls and trenches that would have seriously curtailed any movement east. For it’s true purpose, of course, was control; it crossed (and still crosses) important routes connecting the fen edge to the larger towns like Cambridge. As stated, much of this landscape was defined by water and, originally, the dyke would have completely blocked a narrow land corridor between the water-loggged marshes of the fens, and dense inhospitable woodlands to the south; it was effectively an unavoidable gateway to the lands to the east.

This bullying, mercantile reality pales against the fireside tale that grew out of it. As a tool designed to do a job, the dyke lasted a surprisingly short time and swiftly fell into disuse. By the time Edward the Elder had defeated the Danes in 905, and pushed the invaders back toward the Wash, its role in the Anglo Saxon Chronicles is as a geographical reference point (‘dicun’, simply ‘the Dyke’) and no more. Hrothgar fills this most unusual of gaps. Quite how he fetches up in Cambridgeshire is unclear, although it is surely not too much of a leap to imagine his stories being recounted by visiting sailors and adventurers from beyond the marshy horizon. From 1100 a wharf had meant that it was easy for goods to be loaded into the fen waterway system. Moreover, Reach was a major producer of clunch, a chalky stone used for building.

The little village on the edge of the fens had bumped up against the world, and a population eager to hear stories from beyond its misty borders would have lapped Hrothgar up. It would have embraced him with vigour.

Long ago, before the fen and marsh, the land was covered by a vast and impenetrable forest. Here there lived a race of giants, and their chief was the mighty Hrothgar, a leader of fierce reputation, loved and respected by his people, and also by the creatures, the demons of the netherworld, who lurked in the dark. But one of these demons, who controlled fire, fancied to take Hrothgar’s daughter, Hayenna, for his own. Fearful, Hayenna approached her father who tried to set her mind at ease. He was a fierce ally of the water demon, and could call upon him whenever needed. In a vision, Hrothgar spoke to the water demon, who told him how to combat the fire creature. The water demon told him that the Tempest was now in a terrible alliance against him also, and that he must make preparation. The next day, Hrothgar asked his people to help him and so they pulled up all the trees and bushes until a plain track appeared. Then, they scooped up all the earth, such that a massive trench, some seven miles long, appeared. As they worked, the spirits of the air perceived their plans and informed the Tempest. A foul storm blew up, an explosive tumult of hail and rain and ice, that rocked Hrothgar’s people back on their heels. They admonished him for taking against the gods in such a way, but he stood fast. As he spoke the fire demon crackled into life and stood before the trench, laughing at their work, He lit the ground around him and clothed in smoke and flame advanced upon the horrified workers. All seemed lost, but Hrothgar, never retreating for a moment, leapt into the conflagration and with tremendous strength, smashed the wall between the dry dyke and the nearby river. A vast body of water tumbled into the trench, barring the way of the fire demon. However hard he tried he could not breach this sudden barrier and so the water demon, in close alliance with Hrothgar, banished his sworn enemy.

Reach had been split in half by the dyke, and right up until the 18th Century the two halves of the village were distinct entities, East and West Reach. When it was filled in, the new field was used as the fair green.

I came to Reach to try and catch a glimpse of a new visitor to the area. New that week, I mean, not new overall, although it’s difficult to be sure. Short-eared Owls are an irruptive migratory species; individuals or groups of birds will not follow predictable patterns, but appear suddenly, hang around, move on. They may be members of the indigenous population, or Scandinavian birds leaving behind a colder northern winter to play out. Along this marshy coast, these heathy fields, they pop up from the rough dead grass, for they are primarily ground-dwelling birds, bend their heads to look down into the brown scrub, then twist and re-calibrate, dropping silently onto whatever poor creature is scrabbling by. On the fen north of Reach, about a dozen had arrived and I was eager to see them before they shifted location. The village was silent as I parked up, just after dawn. Short-eared Owls, sometime migratory, mostly ground-living, extend their unexpected repertoire further by hunting diurnally. I wasn’t sure if this meant the middle of the day, or at one or either end, but I figured an early start might increase the possibility of seeing other species. And indeed, as I followed the lode path out of the village, the hawthorn bushes bordering the fields are agitated to overflowing with noisy just-woken life. Robins, greenfinches, chaffinches, linnets scatter and flock across the stream, or over to the next field, undulating and dipping and all the time chirruping needily.

The Lode is still navigable, which I suppose must be for leisure craft, although I’m surprised to discover that the port closed just a couple of hundred years ago. I take the bank as it leads me north and Burwell Fen, Hallard’s Fen, Adventurers’ Fen all open up before me, black-soiled, regimented, rich fields, washboard flat. It is almost fully light and I disrupt a Tawny Owl while pushing through a hedge to look at a fishing pit. Am I too early, or do the Strigidae shifts overlap? The Short-eared Owls are in a field two miles north. It is filled with camouflaging tufty brown grass and borders a herd of grazing deer. As I train on the deer, an owl floats up before them, rests on the breeze for a moment and then lands on a fence post. He scans the ground beneath him, lifts off and drops. I lose him then, but he is replaced by another, and another, all bobbing up no higher than than a few feet. Buoyant, poised, they flap their wings languidly before vanishing into the scrub.

There are people walking through the field, and the display ends. This has become a waking, a woken up landscape. Likely, the birds will move on quickly. It is possible they may work their way inland, to higher and higher grounds, or along the coast to other marshy areas. I head back to Reach, along the Lode path.