1. In 1969, NASA's Apollo 11 mission successfully landed on the moon on July 20. Astronauts Neil Armstrong and Edwin "Buzz" Aldrin became the first humans to walk on the moon, while Michael Collins orbited the moon in the command module.

2. On July 20, 1944, a group of German officers attempted to assassinate Adolf Hitler at his Wolf's Lair headquarters in East Prussia. The plot failed and many of the conspirators were executed, including Claus von Stauffenberg, who planted the bomb.

3. In 1822, Florida officially became a U.S. territory on July 20. Prior to that, it had been under Spanish rule since the 1500s.

4. On July 20, 1976, the Viking 1 lander successfully touched down on Mars, becoming the first spacecraft to do so. It took over 4 years for Viking 1 to transmit data back to Earth.

5. The USS Indianapolis was sunk by torpedoes from a Japanese submarine on July 20, 1945. The ship had just delivered components for the atomic bomb dropped on Hiroshima and was en route to the Philippines when it was attacked. Only 316 of the nearly 1,200 crew members survived.