1520-Hernán Cortés and the Tlaxcalans defeat a numerically superior Aztec force in the Battle of Otumba in Mexico
1807-French Emperor Napoléon Bonaparte and Russian Tsar Alexander I meet on a raft in the middle of the Neman River and sign the first Treaty of Tilsit
1937-Japanese and Chinese troops clash at the Marco Polo Bridge, beginning the Second Sino-Japanese War
1947-Alleged and disputed Roswell UFO incident
1950-Korean War: U.N. Security Council establishes the United Nations Command to combat North Korean forces
2005-Coordinated terrorist bomb blasts strike London's public transport system during the morning rush hour, killing 52 and injuring 700