How does siege climbing on Mount Everest work?

Siege climbing is a traditional, methodical technique used to ascend Mount Everest. It involves a large team establishing a series of tented camps at increasing elevations along a route, typically spaced about 1,500 feet (450 meters) apart.1

The core strategy relies on the principle of "climb high, sleep low." Climbers ascend to establish a higher camp but return to a lower camp to rest, which facilitates acclimatization to the extreme altitude. This process continues until a final camp is positioned close enough to the summit—usually about 3,000 feet (900 meters) below—to allow a small "assault" team to make a final push for the peak.1

This style is characterized by heavy logistical support, often provided by Sherpas, and is frequently utilized by large commercial expeditions. While historically significant, some mountaineers have criticized the siege method as being overly predictable or "unsporting," leading to the rise of the faster, lightweight Alpine style of climbing.1