South of the Brecon Beacons’ popular mountains lies an area of wild moorland, at its midst a huge cave with a fascinating history. Will Renwick headed out to find it

Up we went onto the dark hill. We hadn’t made it to our start point, the Red Cow Inn of Ponsticill village, until just after nightfall. The landlord had waved us off, offering a bit of friendly advice: “Trust me boys, if you see the fog come in, you get down off that mountain right away.” It wasn’t a reassuring remark with which to depart.
Sam and I climbed sharply up the 557m Mynydd Llangynidr, our boots tapping against the rocky track. Soon we reached the moorland plateau and, on a patch of grass cut short by the Welsh Mountain sheep, we threw down our packs to make camp. For the first time since we’d set off, I looked back down the valley that we’d just climbed from. There was Merthyr Tydfil, a gentle red glow above it, the last remnants of light sinking in the west.
This town was once renowned for a red glow of a much less salubrious nature. From the early 19th century until after the First World War, it was the ‘The Iron Capital of the World’, a place filled with vast ovens, their chimneys pouring bright red embers into the sky to create a  fiery light that could be seen from every one of the valleys of South Wales. It was a vision that romantic painters  flocked to capture, their paintings showing chaos and hellfire of biblical proportions – just a normal night in Merthyr Tydfil back then. “There is no green on the mountain after dark,” wrote Alexander Cordell in his 1959 novel, The Rape of the Fair Country. “Sulphur is in the wind then, and the sky is red with furnace glare from Nantyglo to Risca, and when the night shift comes on the world catches alight.”
Into this melting pot gravitated people from all corners of Wales and beyond. The agricultural way of life had started to disappear and those in need of work were forced out of the corn fields to find a living in the coalfield. Between 1801 and 1851, the population of Merthyr grew from 7,000 to 50,000.
Townspeople lived in one-room shacks, their lives in the grip of the ironmasters who, aware of the surplus of labour, were at liberty to set wages as low as they liked, and even to pay workers in their own currency, a currency that could only be used in their own stores. It was a recipe for disaster. And it didn’t take very long for the town, and for the whole of the South Wales valleys, to come to boiling point.
Trouble  first bubbled up with an uprising outside Merthyr Tydfil’s Castle Inn. At least 24 rebels were killed in a chaotic and brief event that saw the  first  flying in Britain of a red  flag symbolising revolution. Afterwards, the discontent became more organised. Merthyr and the rest of the South Wales Valleys were a hotbed for Chartism, a political movement campaigning for rights for the working classes. Revolution was on the lips of those in the ironworks and down in the coal mines, with plotting in the public houses and preparations made on the mountain… the very mountain on which I was pitching our tent and Sam was preparing the dinner.
Somewhere along the plateau there are deep and dark places where the Chartists, in the glow of lanterns, came not only to hide their weaponry, but to create it, putting their day jobs into practice by night in the smelting of iron for pikes and swords.
Sat on the dry ground with our dinner on our laps and some whisky to help us with the cold wind that had begun to blow from the Black Mountains in the east, we did some plotting of our own. Under the beams of our headtorches we marked out the route we would be following through the moorland the next day on our way to locate the most well-known of these hideaways, the one kindly marked by the Ordnance Survey as “The Chartist Cave”. The door to the underworld of the Brecon Beacons would be our destination, perhaps even our shelter for the following night.

A new day awaits

Pitching at night isn’t everyone’s cup of tea, but I’ve come to find it rewarding. I love that moment as I slide open the zip of the tent the next morning, unaware of what will greet me through the portal. Sometimes, it can be disappointing; the time I woke to find I was on the edge of the busy main road into Pembroke being one such example. But this morning was one of the good ones. I pulled back the  flap of my tent, and at first was struck by the fact that the ground had a good inch of snow on it. Then I saw the view. Down in the valley below us, Pontsticill Reservoir extended northwards. A plume of white smoke ran parallel to its forest-filled eastern bank, coming from the steam engine that was making its way towards Pen y Fan. The three distinctive humps of Corn Du, Pen y Fan and Cribyn stood astride from one another, each in an unseasonal coating of snow. Sam wasn’t quite as enthusiastic as I was just yet; a couple of prods – with angry noises in reply – were needed until he could be persuaded to emerge and enjoy the view.
The hard work had been done by our fresh legs last night and now we were on top of Mynydd Llangynidr the walking would be flat for most of the morning. We set off for the moorland’s distant horizon, immersing ourselves in a desert of heather. “You can see what he was on about,” said Sam, recalling the landlord’s warning not to take fog lightly. I agreed. This featureless landscape scored with sheep tracks would be tricky to navigate in even the slightest lowering of cloud. You can see why those plotting for rebellion back in the 1830s came up here for their secret meetings. It would have been a reckless, determined person who chose to wander through this wilderness in darkness to catch them out. Fortunately for us, despite being fully prepared for a wet, navigationally testing weekend (in practice for the approaching TGO Challenge) we had glorious blue skies. And we could soon see not just Pen y Fan, but also the bold outline of the Black Mountains, all waiting for the sun to climb over them and illuminate their western faces. The upper reaches of the peaks, by now, were almost rid of the night’s snowfall.
One of the nearer hills we could see was Tor y Foel, a little conical shape, mischievously breaking off from the mass of Mynydd Llangynidr. Seeking variety from the  flat moorland, we headed straight for it. I’d like to say this was the only reason we were aiming for Tor y Foel, but I’d be  fibbing. We had both noticed on the map that at the foot of its slope, in the Vale of Usk, there was a pub – with the promise of real ale and maybe even a steak pie.
Eventually we were down by the glinting Usk River and found ourselves in the exception of the South Wales valleys: a place full of green and empty of any industrial scars. The Usk valley managed to hold onto its pastoral ways throughout the testing 19th Century and on to this day. Look at a geological map of Wales and you can understand why. The big splodge of grey representing the Carboniferous rock – which was so attractive to those with picks and shovels – occupies most of the central part of South Wales but comes to a sudden halt here, in its place a Silurian and Devonian bedrock.
Having had our fill at the pub, we headed back up to Mynydd Llangynidr and could see that coal-fostering Carboniferous rock for ourselves, exposed in the great outcrops of Llangattwg, dark slabs over the  fields below. The green colours of the valley soon disappeared as we rose up, and were back on the moorland, back in search of our rebels’ cave.
By now the setting sun had caused the heather to turn a fiery orange, and the deep sinkholes that pockmarked the mountaintop quickly filled with shadows. Although it was a spectacular sight, the fading light caused some urgency to our searching. “Where are we supposed to  find this cave then?” Sam asked. “It’s supposed to be just down from one of the cairns,” I told him. “And where would that be then?” I had no idea. Rising only a few metres from the moor, these pimples weren’t as easy to  find as I had hoped. We took some time to locate our cairn, and right there in front of us was the cave.

The Chartist Cave

Although we had dabbled with the idea of bedding down inside, from the very instant I laid eyes on the cave, I knew I wouldn’t be sleeping in it. Not in that deep black eye in the hillside. We approached the hole. It hadn’t rained today, but dripping noises came loudly from the entrance. Scrabbling over a few boulders and ducking our heads slightly, we entered, our eyes taking a few seconds to adjust to the darkness, and to assess the hall we had stepped into.
Chartist cave
It’s likely they would have come here to gather the weaponry together only the night before the rising in 1839. As many as 30 people could fit in here quite easily. I can imagine the torch flares, and the unrestrained voices echoing; they could have been as loud as they liked up here without fear of being heard. I picture them picking up their weapons and making their out of the cave, trudging through the moor in a downpour (accounts mention torrential rain the next morning down in the valleys so it would doubtless have been raining heavily that night).  The view from the cave entrance across the mountain today can hardly be any different from the one of 177 years ago. Eventually the band of rebels would dip below the horizon, making their way down to join up with the generals and their divisions of thousands who would all follow the canals down to Newport for the last large-scale armed rebellion in Great Britain.
After pitching our tent by the entrance of the cave, I went off to a nearby pond to get water to boil. When I returned, Sam was nowhere to be seen. I shouted into the cave and a distant voice replied from a narrow crack at the back. In 1969 a caving club doing some speculative digging managed to discover a network of passages here, of which 400m have now been mapped – but it’s thought they run much further, perhaps twisting through the bowels of the whole mountain. Sam had slipped through the only entrance to the labyrinth, but dared not advance any further.
chartist cave
In reply to scattered musket shots red at the Westgate Hotel, the 45th Regiment of Foot let rip indiscriminately into the crowd. At least 22 people are recorded to have died in the battle in Newport, though it’s thought that many more would have been dragged off to die at home, and subsequently buried in these mountains.  The day was a disastrous failure.  The immediate intention was to capture the Westgate Hotel, and the rebels had come nowhere near to achieving this. Had they done so, some historians believe that the intention would have been to march on to Monmouth, Bristol, perhaps even London, following the lead of the proletarian revolutionaries across the English Channel.  The leaders of the Newport Rising were put to death, but were spared thanks to a petition signed by 1,400,000.  This show of support for the Chartists and their cause sent a strong message to the government, and to Queen Victoria. The fight was a failure on the day, but it was perhaps an eventual success, helping to accelerate the country towards eventually securing a vote for the working man.
We had a clear night, and were able to marvel at Pen y Fan lit by the bright moon. The next morning, having shaken off the frost, we hiked off the mountain, back down to Ponsticill. This time we could see Merthyr Tydfil in broad daylight, that unfortunate town that always appears in ‘Top 10’ lists of unhappy or unhealthy places, but has a proud history worth remembering; a town that most hikers drive straight past on their way to the popular peaks of the Brecon Beacons, but that has a hill above it that’s certainly worth exploring.
RELEVANT: More caves and crannies that are worth a peek