A fascinating way of spending a few hours of leisure is to sit down with a paper and pencil and work out in minute detail the preparations for an expedition into unexplored country. The fact that there is very little chance of carrying out the project matters little. These dream expeditions can be staged in any corner of the world. I have imagined them in the forbidding mountains of Nepal, and in the wind-swept ice peaks of Tierra del Fuego, and across the Antarctic continent.

On the 1936 Everest Expedition, during the tedious hours of a snow-storm on the East Rongbuk glacier, lying in my sleeping bag, I discussed a detailed scheme with Noel Humphreys for the exploration of the remote snow range above the dense, steamy forests in the centre of New Guinea. The plan was to charter a dhow from a Dutch port on the south coast and sail to the southern extremity of the island; then to land with sufficient food and equipment to last one and a half years, and to relay the loads for three hundred miles, following a high ridge, above the fever swamps, that we hoped would lead to the snow range. We contemplated taking a dozen Sherpa porters with us to carry the loads inland and to help us live in the hostile country, and eventually to take part in the climbing. Lest the Sherpas be homesick so far from their country, for so long, we even considered allowing them to take their wives; and we discussed the possibility of planting crops in the foothills to help us live in the interior.

I often amuse myself by making a list of these imaginary expeditions in order of their attractiveness. Sometimes one heads the list, sometimes another. Always one plan is uppermost in my mind, until circumstances determine which shall be attempted.

Talking like this with John Morris, on the way down from Base Camp to Rongbuk, after the 1936 Everest expedition, he asked me if I had ever considered his pet plan of a journey from Hunza to Leh by way of the Shaksgam river. During the march back across Tibet there was plenty of time to discuss this project, and to weigh its possibilities. By the time we reached India it so far headed my list of plans as to exclude the thought of all others.

The Shaksgam river lies somewhere on the undemarcated frontiers of Chinese Turkestan, Hunza and Kashmir. It was necessary to obtain permission from the Government of India to take a party into that area. At the end of July I went to Simla to explain the project to the authorities. Some months later permission was granted. In August, while waiting for the start of a survey expedition to the Nanda Devi basin, I stayed with Bunty and Norman Odling in their lovely home in Kalimpong – a haven for so many travellers; during this pleasant interlude, with the aid of all the existing maps of the Karakoram, I made myself familiar with the geography of that range, studying the various routes, the costs involved, and the difficulties inherent in each plan of approach. Eventually I decided that instead of making the suggested journey it would be more valuable to establish a base in the middle of the Shaksgam area, with sufficient food to last three and a half months, and to make exploratory excursions from there in all directions.

At this stage my plans were necessarily vague, but I was fascinated by the idea of penetrating into the little-known region of the Karakoram. As I studied the maps, one thing about them captured my imagination. The ridges and valleys which led up from Baltistan became increasingly high and steep as they merged into the maze of peaks and glaciers of the Karakoram, and then suddenly ended in an empty blank space. Across this blank space was written one challenging word, ‘Unexplored’. The area is dominated by K2, the second highest mountain in the world, and is bounded on the south by the main Asiatic watershed.

The southern side of this range has been visited by many explorers and mountaineers who have partially surveyed its vast glaciers. But it is the northern side of this great watershed which has proved so difficult of access. The country is inhospitable and uninhabited, and no traveller can stay long in its remote valleys. These are deep and narrow with precipitous rocky sides. The unbridged rivers, fed by the huge glaciers, tend to flood to an enormous depth during the summer months when the ice is melting, and are then quite unfordable.

The first explorer of this part of the Karakoram was Sir Francis Younghusband, then a Lieutenant in the Dragoons. In 1887, at the end of his great journey across Asia, from Peking to India, he crossed the Aghil range, by what has since come to be known as the Aghil pass. This range lies to the north of the Karakoram. On the southern side of the pass he discovered a river which his men called the Shaksgam. From there he ascended the Sarpo Laggo glacier and crossed the main Karakoram range by way of the Mustagh pass. His account of this remarkable feat will be quoted later in this book.

Two years later he again crossed the Aghil pass to the Shaksgam river, which he followed upstream for a considerable distance. He then tried to enter the mountain country to the south-west; but failing to make his way up a great glacier, called by him the Crevasse glacier, he followed, in the late autumn, the lower reaches of the Shaksgam and so reached the Shimshal pass, which lies at the north-western extremity of this area.

Since then other travellers have visited various parts of this region. In 1926 Colonel Kenneth Mason led an expedition, financed by the Survey of India, to the Shaksgam. His object was to cross from the Karakoram pass, which lies at the eastern extremity of the Aghil range, to the head waters of the Shaksgam. From there he intended to work downstream so as to connect up with Younghusband’s route, and to fix the geographical position of the Shaksgam river and of the Aghil pass. His way was barred by a great glacier, which, coming down from the northern slopes of the Teram Kangri range, dammed the Shaksgam river. The ice was so appallingly broken that it was quite impossible for the expedition to cross the glacier and to continue its progress down the river. Mason named the glacier the Kyagar. His party went up into the Aghil range and explored its eastern section. There they were faced by the great difficulties of travelling in an entirely uninhabited area. In August they found another great river, which at first they imagined to be the Shaksgam itself. They failed to follow it down-stream owing to the enormous volume of water which was racing through its gorges. But they went far enough upstream to realize that this river was not the Shaksgam. So Mason named it the Zug – or false – Shaksgam. The lateness of the season forced the party to leave the problem of its course unsolved.

In 1929 a party from HRH the Duke of Spoleto’s expedition crossed the Mustagh pass into the Shaksgam valley, and followed it up to the Kyagar glacier. The work accomplished by this party will be mentioned in a later chapter.

In 1935 Dr and Mrs Visser, who have made three remarkable expeditions in the Karakoram, followed Mason’s route and succeeded in crossing the Kyagar glacier and in mapping the great glaciers coming down from the Gasherbrum peaks on the main watershed. They were prevented from going farther down the river by the summer floods.

But to the west and north-west of the areas visited by these explorers there still remained vast regions of unknown country of absorbing interest to the mountaineer and to the geographer. It was the exploration of a portion of this area that was the main object of my expedition.

We had three principal interests. First, the section that lies between the Sarpo Laggo valley and the Shimshal pass, bounded on the north by the Shaksgam river, an area of about 1,000 square miles. Younghusband had touched the fringe of this country when he tried to ascend the Crevasse glacier. Second, the glacier system lying to the north and north-west of K2. Third, the portion of the Aghil range, west of that explored by Mason’s expedition. The two outstanding problems of this last area were to find the lower reaches and outlet of the Zug Shaksgam river, and to fix the geographical position of the Aghil pass. As 1937 was the fiftieth anniversary of Sir Francis Younghusband’s famous journey, we had an additional incentive to visit this pass. So far as we knew no European had been there since Younghusband’s second crossing in 1889.

The first thing to be decided was how to tackle the problem of getting to the Shaksgam. Apart from attempting to reach it from China, three alternatives were open to us: first, to cross from the Karakoram pass to the head waters of the Shaksgam and make our way down over the difficult glacier trunks which had defeated Mason’s party in 1926; second, to cross the Shimshal pass early in the spring, and force a route up the lower gorge of the Shaksgam before the river became too high; and third, to cross the main Karakoram range from the Baltoro glacier. The first two alternatives would probably have involved considerable difficulties with the river even early in the year, and would have rendered us liable to be cut off by the summer floods until late in the autumn. Besides this, the journey either to the Shimshal or to the Karakoram pass is very long and costly, particularly early in the year when the routes are not officially open. The difficulties involved by the third alternative, the crossing of the main Karakoram range, were of a purely mountaineering character,...