- "The war is over, and we are in control, as planned."
- ―A Templar letter regarding the war, 1945.[src]
World War II, or the Second World War, was a global military conflict lasting from 1 September 1939 to 2 September 1945. The war involved most of the world's nations, including all of the great powers that eventually formed two opposing military alliances: the Allies and the Axis.
When the Medjay Bayek of Siwa visited the Eeyoo Sekedoo Aat complex in Haueris Nome during the 1st century, he triggered an encoded message inaudible to him from an unidentified female Isu that foretold future historical events, among which were "families cowering in fear as V2's vaporize their dwellings".
World War II was the most widespread war in history, involving more than 1.9 billion soldiers. In a state of "total war," the major participants placed their entire economic, industrial, militaristic, and scientific capabilities towards the service of the war effort, erasing the distinction between civilian and military resources. 
Marked by significant events involving the mass death of civilians, including the Holocaust and the only use of nuclear weapons in warfare to date, it was the deadliest conflict in human history, resulting in between 50 to 80 million fatalities. 
The war began on 1 September 1939, with the German invasion of Poland, the subsequent invasion by USSR on 17 September, followed by the subsequent declarations of war on Germany by France and most of the countries of the British Empire and the Commonwealth. 
The war ended with the total victory of the Allies over Germany and Japan. Germany surrendered 8 May 1945 after the fall of Berlin and collapse of German battle lines.  In early August 1945, the United States dropped nuclear bombs on Japan, one on Hiroshima and another on Nagasaki. Japan surrendered unconditionally on 2 September 1945.
- "H. and S. brought on the turmoil and fear necessary, now we must strike fast to ensure development continues in the proper direction."
- ―A Templar agent, in a speech delivered to Templars worldwide, 1944.[src]
The Templars began the war in an effort to form a new world government, creating the chaos necessary to install an international monetary system which was later proposed at the Bretton Woods Conference. Winston Churchill, Joseph Stalin, Franklin D. Roosevelt, and Adolf Hitler were the world leaders confirmed as Templar puppets. Hitler and Roosevelt were the only leaders confirmed to hold Pieces of Eden.
The original plan for the conclusion of the war called for a Hitler double to be found cremated in the "Führerbunker", so that Hitler himself could escape from a besieged Berlin to rendezvous with Churchill. However, the Assassins killed the original Hitler as he departed from his bunker. It is unclear what happened to Hitler's Apple after his death.
Roosevelt, whose health had slowly deteriorated over the course of the war, died of a stroke shortly before the war's end, with Vice President Harry Truman taking his place and eventually ordering the bombing of Japan.
- Assassin's Creed II (Glyphs only)
- Assassin's Creed: Initiates (mentioned only)
- Assassin's Creed: Unity (first appearance)
- Assassin's Creed: Conspiracies
- Assassin's Creed: Origins (indirectly mentioned only)