May 26: First Assault by Evans and Bourdillon from the South Col using closed-circuit oxygen sets. The same day Hunt leads a party of Sherpas from the South Col with the intent to establish Camp IX on the SE Ridge for the second assault party consisting of Hillary and Tenzing. Evans and Bourdillon reach the South Summit at 1 PM at an elevation of 28,750 feet (8770 meters), but are forced to descend due to the lateness of the hour, strong winds, and lack of oxygen.
May 29: Second Assault by Hillary and Tenzing using open-circuit oxygen sets. They leave Camp IX at approximately 27,900 feet (8500 meters) by 6:30 AM, and reach the S. Summit by 9 AM. After negotiating the 40 foot (12 meter) Hillary Step, they are the first to reach the summit of Everest, reaching the top at 11:30 AM. After descending to the South Col, they are met by George Lowe where Hillary states: "Well, George, we knocked the bastard off!"