It was decided that Houston and Paul Petzoldt would make the last push to get as close to the summit as they could and then rejoin the rest of the party in descent.

A suitable route up the Abruzzi Ridge had been explored in detail, good sites for tents had been found (sites that would go on to be used in many future expeditions), and they had identified the technically most difficult part of the climb, up House's Chimney at 22,000 feet (6,700 m) (named after Bill House, who had led the two-hour climb up the rock face).

The mountain had been spotted in 1856 by the Great Trigonometrical Survey to Kashmir[note 2] and by 1861 Henry Godwin-Austen had reached the Baltoro Glacier and was able to get a clear view of K2 from the slopes of Masherbrum.

The expedition examined ascent routes both north and south of the mountain and made the best progress up the northeast ridge before they were forced to abandon their efforts.

[11] Since that time K2 has developed the reputation of being a more difficult mountain to climb than Mount Everest – every route to the summit is tough.

[12][note 4] The 1909 Duke of the Abruzzi expedition reached about 20,510 feet (6,250 m) on the southeast ridge before deciding the mountain was unclimbable.

[15] In 1929, Aimone de Savola-Aosta, the nephew of the Duke of the Abruzzi, led an expedition to explore the upper Baltoro Glacier, near K2.

Although Wiessner had been expected to lead the first expedition – he was probably the best American mountaineer and climber at the time – he backed down and suggested Houston replace him.

[21] Following the British example, and unlike Wiessner's expedition next year, they took very little technical climbing equipment – only ten pitons were thought sufficient.

Sherpas are of Tibetan and Nepali origin but those seeking a career in mountain guiding based themselves at Darjeeling in India where pre-war British Everest expeditions had always done their recruiting.

[30] Benefiting from the work done twenty-nine years earlier by the Duke of the Abruzzi expedition, Houston's party set out to review the various possible approaches to the summit.

Again they were thwarted so as a consolation they climbed high on Chogolisa, to about 24,275 feet (7,399 m) – the highest altitude ever reached and one that would not be exceeded until the 1922 British Mount Everest expedition.

They had been hoping to find a route from this side because the 1909 survey had observed that the rock strata on the northwest ridge provided a step-like climbing route whereas on the other side, the Abruzzi Ridge, the rocks sloped downward giving insecure footing and poor places to pitch tents.

[33] below Bottleneck Couloir (26,900 ft (8,200 m))[46] Camp II was established on July 3, but right at the start, there was a serious accident when a rock fell on a can containing most of the supply of cooking fuel, spilling all the oil.

Streatfeild led a small party to the foot of Gasherbrum, hoping to find the supply left by a French group in 1936.

Pemba Kitar, and the cook, Ahdoo, went off down to Askole, a march expected to take seven days, to get porters to bring up a supply of firewood.

Rocks dislodged by climbers higher up the mountain fell 500 feet (150 m) punching holes in all three tents but fortunately no one was hit.

In those days pitons were of rather soft metal and were ineffective on a hard rock so at 21,500 feet (6,600 m) House effectively had to free climb his way up the chimney without protection because there were no alternatives for getting further up the ridge.

Concerned in case bad weather would delay a descent, they decided by a vote that Houston and Petzoldt would be the climbers to up to as high as possible.

[53] It was thought that the mountaineering was now technically too difficult for Sherpas so that only the four sahibs would carry supplies up to establish Camp VII – however they agreed to include Pasang Kikuli after he had pleaded with them.

[45] At that point, Houston could go no higher and they turned back at 16:00 after Petzoldt had reached about 26,000 feet (7,900 m) where he found a site suitable for a tent for a future expedition.

[57] Below Camp III on the way down Pasang Kikuli shouted out when he spotted a large rock shooting down towards them and they were only just able to take cover in time.

Eleven more days took them to Srinagar – they were able to take a shorter route over the Skoro La pass and across the Deosai Plains because the snow had cleared since their outward trek.