The 1975 British Mount Everest Southwest Face expedition was the first to successfully climb Mount Everest by ascending one of its faces rather than along its ridges. In the post-monsoon season Chris Bonington led the expedition that used rock climbing techniques to put fixed ropes up the face from the Western Cwm to just below the South Summit. A key aspect of the success of the climb was the scaling of the cliffs of the Rock Band at about by Nick Estcourt and Tut Braithwaite.

Two teams then climbed to the South Summit and followed the Southeast Ridge to the main summit – Dougal Haston with Doug Scott on 24 September 1975, who at the South Summit made the highest ever bivouac for that time, and Peter Boardman with Pertemba two days later. It is thought that Mick Burke fell to his death shortly after he had also reached the top.

British climbers reached the summit of Everest for the first time in an event that has been described as "the apotheosis of the big, military-style expeditions". Bonington's route was climbed alpine style over a decade later in the 1988 Czechoslovak - New Zealand Mount Everest Southwest Face Expedition.

Background Rock climbing in Britain after World War II After years of stagnation between the wars, British rock climbing underwent a renaissance, particularly with working-class climbing clubs starting up in the north of England and Scotland. The Rock and Ice Club in Manchester, the Creagh Dhu Mountaineering Club in Glasgow and several university climbing clubs were amongst those that engendered a highly competitive climbing environment. At Clogwyn Du'r Arddu in Wales numerous routes of a very high standard were achieved using strictly free climbing techniques. Hamish MacInnes and Dougal Haston, although not members, climbed with Creagh Dhu. MacInnes had mentored Bonington's youthful climbing as early as 1953. These associations led on to spectacular exploits such as the American-led direttissima route up the North Face of the Eiger in the winter of 1966 (including Haston) and the televised climbing of the Old Man of Hoy in Orkney in the following year (including Bonington and Haston). The public took notice and commercial sponsorship started to become a possibility for even more elaborate expeditions but with an ultimate aim of rock climbing. With all the 8000-metre peaks climbed by 1964, climbing in the Himalayas using rock climbing routes became an aspiration.

Bonington's path to Everest Bonington's climbing career began when he was still in his teens and he was soon achieving technically difficult ascents in the Alps with several first ascents and, in 1962, the first ascent by a Briton of the Eiger's Nordwand. He made first ascents of Annapurna II (1960) and Nuptse (1962). His role as climbing photo-journalist on the "Eiger direttissima" in 1966 attracted attention and he was encouraged to mount his own expedition.

Bonington conceived of the idea of climbing Annapurna by its South Face which he realised was going to require siege tactics as well as rock climbing. What was to become the 1970 British Annapurna South Face expedition involved Haston as well as such climbers as Don Whillans, Mick Burke, Nick Estcourt, Martin Boysen and Ian Clough (Clough was killed during the descent). The expedition was a success because not only was the summit reached but it was, for its time, the most difficult technical climb to the summit of a major world peak. Bonington had been the leader and had not personally attempted to reach the summit. He was a good communicator and he had been able to attract sponsorship and maintain a group of proficient yet individualistic climbers as a coherent team.

Seizing an opportunity for an Everest expedition post-monsoon in 1972, Bonington originally planned a lightweight expedition by the normal route but the failure of a European pre-monsoon Southwest Face expedition earlier in that year encouraged him to attempt the Southwest Face instead. In very poor weather Bonington's expedition failed to reach the summit but the team gained a great deal of experience, in particular discovering that the line they had chosen above Camp 6 was not as favourable as they had anticipated.

Bonington decided not to make any further post-monsoon attempts but the next suitable slot was a long way in the future so, after learning that a British Army team was planning a pre-monsoon 1976 expedition, Bonington tried to persuade them to allow his team to be included. However, his suggestion was rejected.

Climbing on Everest prior to 1975 Routes climbed After the 1921 British reconnaissance, attempts to climb Everest had been from Tibet because Nepal was closed to foreign climbers. Then, in 1950, Tibet's borders were closed when it was occupied by the People's Republic of China and by that time no expedition had been able to reach the summit. Partly on account of the political situation in Tibet, Nepal started allowing climbers entry in 1950 although it closed its frontiers again in 1966. During the period 1950–1966 three ridge routes were pioneered to reach the summit – the South Col—Southeast Ridge (1953 expedition), West Ridge—Hornbein Couloir (1963 expedition) and by a Chinese team via the North Col—Northeast Ridge (1960 expedition). However, no summit attempt had been made on routes up any of Everest's faces. Nepal again allowed entry to climbers in 1969 and the Southwest Face, the only face accessible from Nepal, was such an attractive objective that Japan immediately mounted a spring reconnaissance in that year and returned in the autumn with a larger party with several climbers reaching on a line striking left from the central gully (black—cyan route on the diagram below).

Previous summit attempts using the Southwest Face

Spring 1970 Japanese expedition – the expedition climbed no higher than in the previous year (black—cyan route on the diagram). However, led by Saburo Matsukata, a party reached the summit via the South Col.

Spring 1971 International expedition – led by Norman Dyhrenfurth, the expedition reached (attained by Haston and Whillans) on a new line leading to the right above Camp 5 (black—blue—brown route).

Spring 1972 European expedition – Felix Kuen and Adolf Huber reached about in an expedition led by Karl Herrligkoffer (black—blue—green route).

Autumn 1972 British expedition – on the Bonington-led expedition was reached by Bonington, Ang Phu, MacInnes, Scott, Burke and Haston (black—blue route).

Autumn 1973 Japanese expedition – was reached on the Southwest Face (black—blue route) but the expedition did reach the summit by the South Col. The expedition was led by Michio Yuasa and it was the first time Everest had been climbed after the monsoon.

Genesis of the 1975 expedition The post-monsoon Japanese expedition in autumn 1973 had attempted both the Southwest Face and the normal route. The face party had failed in much the same way as the British had the year before but the South Col team had managed what turned out to be a very significant achievement. In the post-monsoon season they had reached the summit by climbing directly from the South Col without stopping overnight. By the time they had reached the summit they were out of oxygen but despite that, and having to bivouac overnight without food, drink or a tent, they had returned safely to the South Col.

In December 1973 Bonington heard that a team had withdrawn from its 1975 time slot. It was for post-monsoon so when he applied for the slot he was again intending to attempt his lightweight South Col—Southeast Ridge scheme. Permission was given in April 1974 when he, Haston and Scott were starting on a Changabang expedition (which was to be another first ascent) and Haston and Scott were able to persuade Bonington to try the Southwest Face again, despite it having to be in the autumn. The scheme eventually turned into what has been described as "the apotheosis of the big, military-style expeditions".

Preparations A lesson learned from the 1973 Japanese expedition (and the 1952 Swiss expedition) was that any attempt should be as early as possible after the monsoon was over and this meant the trek from Kathmandu to Base Camp had to be during the monsoon. Another attempt using the "Whillans Chimney" above Camp 6 would have meant establishing a seventh camp and so a route to the left of the Great Central Gully would be taken on the same line that the earliest Japanese climbers had tried. Camp 6 would be established on the upper snowfield and a long traverse would be taken to the Southeast Ridge. To complete the traverse, climb the ridge, and return would be a very long day – a bivouac on the return might well be necessary. To get into a position to do this a large support team would need to make a rapid ascent up the central gully so very careful logistical planning would be necessary. Supplementary oxygen would be used above Camp 4 for climbers and Camp 5 for sherpas. of fixed rope would be used up the face (fixed rope in the Icefall and climbing rope would be additional).

A management committee, chaired by Lord Hunt (John Hunt of the 1953 British Mount Everest expedition), was set up for what would be an expensive, siege-style operation. Peter Boardman was later to remark "for a mountaineer, surely a Bonington Everest expedition is one of the last great Imperial experiences life can offer." Bonington and his agent knew a director of Barclays Bank International and they approached him to see if the bank would provide sponsorship. Barclays not only agreed to provide the £100,000 requested but agreed to cover any overspend. This caused complaints from customers of the bank and a question was asked in Parliament.

In an era before personal computers, meticulous logistical planning was done on a mainframe computer owned by Ian McNaught Davis's computer firm and programmed by a professional programmer.

Expedition team The team was based on the climbers in the 1970 Annapurna and 1972 Southwest Face expeditions. Hamish MacInnes was to be deputy leader and Dougal Haston, Doug Scott, Mick Burke, Nick Estcourt, Mike Thompson and Martin Boysen agreed to take part. All except the last two had Southwest Face experience. People joining the team for the first time were Peter Boardman, Paul ("Tut") Braithwaite, Ronnie Richards, Dave Clarke, Allen Fyffe and Mike Rhodes. Rhodes was a Barclays employee, nominated by the bank. The doctors, both experienced mountaineers, were Charles Clarke and Jim Duff. Camp managers were Adrian Gordon and Mike Cheney who both spoke Nepali. There was to be a team of thirty-three climbing sherpas with Pertemba as sirdar and Ang Phu as deputy. Twenty-six porters for the Khumbu Icefall were led by their sirdar Phurkipa. There were further sherpas for general duties.

In addition there was a Sunday Times reporter and four people from the BBC to make a television documentary, all with their accompanying sherpas. A team of drivers was needed for transport to Kathmandu.

Equipment