Mallory organised a third unsuccessful attempt on the summit, departing as the monsoon season arrived. While Mallory was leading a group of porters down the lower slopes of the North Col of Everest in fresh, waist-deep snow, an avalanche swept over the group, killing seven Sherpas. The attempt was immediately abandoned, and Mallory was subsequently accused of poor judgement, including by expedition participants such as Dr. Longstaff.: