The major historical event that took place on July 20, 1969, is the Apollo 11 moon landing, when humans first set foot on the moon. American astronauts Neil Armstrong and Buzz Aldrin became the first and second individuals to walk on the lunar surface, while Michael Collins piloted the command module in lunar orbit. Armstrong's famous words, "That's one small step for [a] man, one giant leap for mankind," captured the significance of this monumental achievement in space exploration. The mission marked a pivotal moment in history and symbolized human ingenuity and determination.