1388– During the Battle of Buyur Lake, General Lan Yu leads a Chinese army forward to crush the Mongol hordes of Toghus Temur, the Khan of Northern Yuan.
1980–South Korean students in Gwangju begin pro–democracy protests, which are violently crushed, killing 297.
1980–Mount St. Helens in Washington state erupts. A large amount of destruction is caused as many trees and wildlife die, and darkness falls over the nearby area. 57 people are killed, including Harry Randall Truman, who famously refused to leave the area prior to the eruption. It is the costliest volcanic disaster in US history.