Chris Bonington led the expedition, which approached up a glacier from the Annapurna Sanctuary and then used rock climbing techniques to put fixed ropes up the steep South Face.

The Annapurna massif is in the Eastern Himalaya region of Nepal, where for over one hundred years the ruling Rana dynasty had not allowed explorers or mountaineers to enter the country.

At Clogwyn Du'r Arddu in Wales, numerous routes of a very high standard were achieved using strictly free climbing techniques.

[10] Harlin fell to his death and Haston's success on the route were reported on by Bonington and Mick Burke who were on the North Face as climbing journalist and cameraman.

[15] With financial support for the expedition from the Mount Everest Foundation, Bonington assembled a team from amongst his friends: Nick Estcourt, Martin Boysen, Ian Clough, Mike Thompson, Burke, and Haston.

Advised to include an American to boost sales of the book he was planning, Bonington appointed Tom Frost who had considerable big wall experience in Yosemite as well as – secretly at the time – Nanda Devi on a CIA mission to install a nuclear-powered listening device for monitoring Chinese missiles.

Whillans was to be deputy leader for, although by then he was an overweight heavy drinker and smoker who disliked Bonington, he had more Himalayan experience than any other British mountaineer still active.

Unlike twenty years earlier when Herzog had no satisfactory map and had to pioneer a route, by 1970, the track was well known even to hippie wanderers.

[note 2] Another change was that the Sherpas were no longer unsophisticated peasants – they were smart in appearance, spoke good English and had a Western attitude.

[25][26][27] On 16 March, Whillans, Thompson, and two Sherpas went ahead of the main parties to reconnoitre the route and to find a suitable place for the base camp.

The porters returned to Pokhara from where many of them would help move up to Base Camp, the main baggage being carried from Bombay by the party led by Clough, Thompson, and Kent.

For a short distance the route was seriously threatened by an ice overhang which they called the "Sword of Damocles," but they decided to reduce the risk by moving under it as quickly as possible.

[57] When he arrived with the main baggage, Clough was supposed to stop at Hinko Cave overnight on 7 April, but due to confusing instructions, he continued on in a snowstorm with his entourage of 240 porters to temporary base camp some miles further on.

Some porters had refused to go beyond Hinko Cave and the rest, overloaded and without adequate clothes and shoes in the bad weather, variously got into states of anger and collapse.

[60] The version used on Annapurna, designed by Whillans, was cuboid in shape, 6.5 by 4.0 by 4 feet (2.0 m × 1.2 m × 1.2 m), made of socketed aluminium tubes covered in nylon top and bottom and cotton-terylene at the sides.

However, this turned out to be much more difficult than they had expected, with snow too soft and loose for firm piton placements; there would be a need to set fixed ropes all the way up the ridge.

Bonington wrote to his wife, "He is a convinced and fervent Mormon, never rams it down your throat, yet his faith has given him a code of conduct that puts him way out in front of most of us.

[71] Boysen and Estcourt tackled the upper part of the Ice Ridge above Camp IV, which was very narrow with cornices to the left but solid rock on the right.

At 22,350 feet (6,810 m), the slope suddenly changed from 45° to vertical, and this point was intended to become Camp V[note 11] where a 18-pound (8.2 kg) hooped tent was set up, capable of sleeping three.

The climbers further down the mountain were having to rest due to illness or exhaustion, so shortages of rope, oxygen, tents, food and fuel built up towards Camp V. On 12 May, Burke and Frost made more progress, but only through taking serious risks with inadequate piton placements.

In fact, it was Estcourt and Boysen's turn to force the route upwards, but they had been working hard doing carrying while Whillans and Haston rested.

Over the radio between various camps, some of the adversely affected climbers complained, but accepted after Bonington agreed that Whillans and Haston would do a single carry before rotating into the lead.

Whillans then started criticising Burke and Frost for making very slow progress on the Rock Band and so, to curtail the increasing bitterness, the radio call was ended, leaving each pair to plan the detail of their newly assigned roles.

[note 14][84] On their last day in the lead, Burke and Frost, possibly goaded by the criticism, managed to fix ropes up all the way to the Flat Iron.

[91] In terrible conditions on 24 May, Bonington and Clough managed a carry to Camp VI but found Haston and Whillans had been forced back there.

Leaving Camp VI about 07:00, without supplementary oxygen because they had none, Whillans and Haston reached the snow field at 11:00, where they could see the summit through breaks in the cloud.

[93][92] The last fifty feet of the ice cliff was vertical, though there were good holds, and as they reached the northern side of the mountain, the wind dropped.

Due to static on the radio he did not hear the reply "Aye, we've just climbed Annapurna" but this was heard loud and clear at Base Camp and the news spread rapidly up the mountain.

[97][98] Burke and Frost wanted to make their own attempt on the summit and, contrary to his better judgement, Bonington agreed, subject to the clearing of the camps proceeding at the same time.

[note 15] His body was carried down to base camp and he was buried at the foot of a face where Clough had taught the Sherpas and the television crew to use jumars and to abseil.