Back in 2003, the original Call of Duty was released, starting the entire franchise, and its newest project is a homage to that as it is claimed to be going back to the roots.
Ahead of the big reveal of Call of Duty: WWII, Activision gave a brief history of its other World War II games, taking a look at the original, as well as Call of Duty: United Offensive, Call of Duty: Finest Hour, Call of Duty 2, Call of Duty 3 and Call of Duty: World at War.
In between Call of Duty 3 and World at War, the franchise began the Modern Warfare series, which would see a break from WWII, spawning three games and a remaster, before beginning the Black Ops series, which was prologued by World at War.
Since 2012's Call of Duty: Black Ops 2, the series has been set in the future.
With the franchise's expansion, it has recently moved into the realms of sci-fi; the last game before this release, Call of Duty: Infinite Warfare, was set in the future and centred around a battle for the Solar System.