THE NIGHT WE WERE HOPELESSLY LOST ON GREAT MOSS CROSSING

THIRTY years ago, a calm, motionless autumn night in Glen Feshie. We emerged from the car at Auchlean at 3am, aiming to take advantage of the cooler hours on our way to Monadh Mor and Beinn Bhrotain.

First light was struggling to make an entrance as we set off up the Carn Ban Mor path. We were pleasantly surprised to be able to travel at an unhurried – and unharried – pace, the anticipated midge hordes notable in their absence.

Tackling these two Munros from this direction meant reaching the high point of the path then dropping down and over that notorious high-level stretch of bleakness, the Moine Mhor (the Great Moss), before we reached our targets.

It's a lengthy outing no matter which way you do these hills, but travelling from the west we felt the journey was shorter and on better roads than the alternative to Braemar even though the walking would be longer and over tougher terrain.

As we gained height we quickly became swallowed by the mist. No worries though, the forecast was for fine conditions with the cloying grey blowing away as the morning progressed. Anyway, the first two hours were all on path and track so even if the timing of the great clearance was off we should still be enjoying the views before too long. Unfortunately, that timing was way, way out.

When the track ran out we were faced with an invisible landscape. Now we had to navigate across this great expanse described by the late Irving Butterfield as 'the ultimate in desolate wilderness, a landscape so featureless that it almost defies man's ability to use map and compass'. He wasn't wrong.

The next few hours were spent dodging round undulating patches of bog and tussock, little lochans that seemed to instantly loom out of the mist and sodden ground with rivulets running everywhere. We had banked on finding the right moment to start the ascent of Monadh Mor and had Loch na Stuirteag as a back-up in case we overshot. We never found it. Instead we continued walking, constantly gaining height. The compass was showing us as slightly offline but because we were still going up we pressed on. Surely we would stumble across the first summit soon? After what seemed an eternity of constant climbing, we came to a good path running across the top of the slope. Visibilty was still non-existent however, and this path appeared to be along the edge of a huge drop. The wind was blasting up from the colourless maw beneath our feet – it wasn't cold but it carried a seriously damp intent that chilled immediately.

Then we reached a cairn. It was certainly too insignificant to be one of our hoped-for summit cairns but at least it was a marker. Hours behind time and hopelessly disoriented, we still had hopes that we could find our hills. And finally the mist started to dissipate.

Now we were looking back the way we had come to a high pyramid soaring into the fast clearing skies. It took a minute to get our bearings, but I knew for certain this was not Monadh Mor: it was Sgor an Lochain Uaine, the Angel's Peak. The cairn I was sitting at was on Carn na Criche, an outlying top of Braeriach: we were some three miles away from where we had been aiming. Any thoughts of Monadh Mor and Beinn Bhrotain now abandoned, we managed to salvage something from the trip by heading over Sgor an Lochain Uaine and then on to Cairn Toul. The walk back was long and weary, we managed to arrive back in Glasgow late for a work start of 4pm. Still, at least we hadn't slept in.

It was biggest navigational error I had ever made, and still is to this day. It so enraged and gnawed away at me that just two weeks later I went back. Same place, same time – I was determined to put the record straight. Unfortunately, it was Groundhog Day. The conditions were exactly the same, although this time I managed to punch through the early mist and arrive at the summit of Monadh Mor with the cloud base beneath my feet. A Cairngorms inversion at 6am, dark, shark fins sticking out of the sea of white all around as I made my way over to Beinn Bhrotain. Magnificent.

I don't remember much of the journey back, this was sleepwalking at its finest. I even allowed myself a couple of hours' kip in the car park.

Since then, I have been on all of these summits multiple times but always come in from the more traditional routes from the north or east: the Feshie start has only been used for the hills directly above the glen. Until last week, that is. After 30 years it felt right to revisit the scene of that monumental wayfinding blunder to figure out exactly where I had got it so wrong.

A club meet to Glen Feshie allowed three of us the opportunity to make the crossing to Sgor an Lochain Uaine and Cairn Toul but the conditions were literally night and day – we would be walking in full light, the weather was calm and clear and we all had electronic mapping as well as map and compass.

Dropping over the brow into the Moine Mhor the vastness of this bleak landscape immediately becomes apparent: even though the mountains are huge they appear dwarfed due to this expanse and the distances needed to reach them.

The notoriety of the Great Moss is undiminished. It's also beautiful. Granted, not in the traditional sense of beauty but in a more intense, challenging way. The lack of birdsong and animal life merely enhances the slightly eerie atmosphere.

I have since heard it described as the 'graveyard for potential mountain leaders' and, more colourfully, as a 'slough of despond', a reference to a fictional bog in The Pilgrim's Progress which has become synonymous with depression.

Braeriach's muscular shoulders were carrying towering, roiling clumps of dark grey and black cloud, while Sgor an Lochain Uaine's summit seemed to be thrusting its way up through the blanket and mighty Cairn Toul was almost an afterthought. Monadh Mor just lay there, insignificant from this angle and fronted by Tom Dubh, a rounded grassy swelling that is logged as a Munro Top but which looks embarrassed at being anywhere near this company.

In this perfect clarity, it was easy to spot the way ahead but there was still a lot of fancy footwork needed to negotiate the terrain. And all the while as we made progress, I struggled to get my head round how far off route we had been on that first crossing.

It seemed impossible we could have been on the lower slopes of Monadh Mor but ended up on Carn na Criche. I had assumed we had walked over the edge of the former and then been pushed further and further north, tempted or seduced by the constantly rising angle of the ground. We had obviously never made it as far as Loch nan Stuirteag, and it now seems more likely that we had always been further away from this body of water. But that should have taken us directly up Sgor an Lochain Uaine rather than even further over to Braeriach. I can only think that at one point we stopped trusting the compass entirely and decided to go for the heights in a bid to find out exactly where we were.

The advantage of full sight this time meant we had the luxury of cutting out some of the bog and heading straight for the rising ridge, the only obstacle being the fast-flowing stream enhanced by snow melt that needed some delicate steps to cross dry-footed.

As we gained height fast, the landscape became more and more expansive and we could spot tiny figures high on the skyline. It wasn't long until we joined their company on the rim. Carn na Criche was revealed in all its glory over the massive cornices still clinging on determinedly all along the edge, then the full bulk and majesty of Braeriach. The blindingly white fringe continued all the way to the col with Cairn Toul and all the way up again to the summit cairn. We clambered back down over the huge boulders then continued on a rising line over the side of Sgor an Lochain before curving round to face the bog once more.

I don't remember how we made our way back all those years ago, the only memory was that it was exhausting. Even now, our pathless passage took a toll: it's easy to forget there will be some re-ascent to get back out and the relief for weary legs when we finally hit the track was palpable.

It's not a route I intend doing again anytime soon, but having the chance to understand how easy it can be to get it so wrong in this vast mountain landscape was invaluable, well worth the hours and the effort.