The USS "Arizona" (BB-39) was an American battleship from the Pennsylvania Class. The building of the ship was started in 1913 and it was commissioned in 1916. It fought in World War I. The USS "Arizona" is best known for its sinking during the Japanese attack on Pearl Harbor on December 7, 1941. The attack was the event that caused the United States to join the fighting in World War II. The wreck is still at the floor of the harbor. It is the site of a memorial to those who died that day.