World War II

World War II, also referred to as the Second World War and regularly shortened to WW2 or WWII, is an event mentioned throughout the Fallout series.

Fallout/2/Tactics

 * Images depicting events leading up to and in World War II appear in the Fallout intro.
 * The 9mm Sten Gun is mentioned as developed by the British during the war.

Fallout 3

 * In the Museum of History, there is an inaccessible World War II exhibit, the archway reading "1941-1945 American Military Might of World War II."
 * Abraham Washington is in possession of the United States' 1941 declaration of war against Germany.
 * The atomic bombing of Hiroshima and Nagasaki is mentioned.
 * The sinking of the USS Ebon Atoll was described as "one of the most tragic disasters in U.S. Naval History since World War II."
 * An exhibit at the Museum of Technology displayed World War II fight medals awarded to pilots, including the Medal of Honor, Distinguished Service Cross, Silver Star, Distinguished Flying Cross, Navy Cross, Air Medal, Bronze Star, and the Purple Heart.

Fallout 4

 * The male Sole Survivor's great-great-grandfather served in the U.S. Army during World War II.

Fallout Tactics

 * The atomic bombing of Hiroshima is mentioned in the intro.

Behind the scenes

 * According to the Fallout Bible, the timeline of the real world and Fallout worlds began to split after World War II. The game series is described as, "drawing gamers into alternate history, diverging from existing reality shortly following WWII" in a Bethesda Softworks lawsuit document.
 * In the Fallout intro, several real world images of the war are shown as the credits roll, seen below.