on may 22, unsoeld and hornbein completed the first ascent of the west ridge, descending by the south col, thus completing the first traverse of everest. that same day, bishop and jerstad reached the summit by the south col route. the two pairs of climbers met up high on the mountain, and made their descent in the gathering darkness. from midnight until 4:00 am, they bivouacked high on the mountain, without sleeping bags, tents or bottled oxygen. all survived, though unsoeld and bishop suffered from frostbite, resulting in the amputation of toes.