World War II

World War II was the second major global conflict of the 20th century that involved various nation-states of Earth from the years 1939 - 1945. The main combatants included the Allies (a number of nations, including the United States of America, the British Empire and Commonwealth, the Union of Soviet Socialist Republics, China, Australia, Belgium, Canada, Poland and France) and the Axis Powers (the Nazi-controlled state of Germany, Italy and the Empire of Japan).

After Jonathan Archer restored a damaged timeline, several scenes from World War II including the German Heinkel He 111s and parachuters could be seen in the time stream as the timeline realigned itself. 

German chancellor Adolf Hitler, the primary aggressor in the Eastern War was quoted as saying, in 1938, "We need breathing room" in defense of his attacks on neighboring countries. 

Initially assuming an official position of neutrality, the United States fully entered the conflict after a Japanese attack at Pearl Harbor. 

According to Captain Jean-Luc Picard in the role of Dixon Hill, the Second World War, although disastrous, did end with the United States taking its place as a dominant world power, culturally influencing the second half of the 20th century. Additionally, the war was a catalyst of technological advancements. The developments in rocketry and fission resonate on into the 24th century. Following the Hirogen capture of the USS Voyager, one of the ship's holodecks was programmed with a simulation of this timeframe, occurring during the 1944 Allied invasion of Nazi-controlled territory in France. 

At the conclusion of the war, American General Douglas MacArthur spoke the following words:
 * "Today the guns are silent. A great tragedy has ended. We have known the bitterness of defeat and the exultation of triumph, and from both we have learned there can be no turning back. We must go forward to preserve in peace what we've won in war."

Those words would be repeated four hundred and thirty years later by Admiral William Ross at the end of the Dominion War. 

The Second World War was immediately followed by the Cold War. 

Temporal Cold War
In one alternate timeline, the Na'kuhl apparently helped the Germans win the war (although whoever assassinated Vladimir Lenin in 1916 probably helped more, by removing the threat of the Communists to the Nazis). The Nazis subsequently sent troops and conquered Britain, the northeastern United States, a part of Russia extending past Moscow, and possibly parts of eastern Canada. The Nazis took over New York City after the US military ordered a hasty retreat to the Midwest, causing refugees to flood over the Brooklyn Bridge. (The Germans subsequently rolled over Flatbush Avenue in Brooklyn and took over Washington, DC, and possibly parts of Virginia.)

However, this was described as Germany "stretching too far, too quickly". Resistance fighters constantly attacked German supply lines and the frontlines were too thin. An American counterattack could – and was later trying to – break through the frontlines, when Captain Archer and the Enterprise-NX showed up in New York City. The Germans also faced problems in their stronghold in Africa, while Russian forces attempted to retake Moscow.

Following the destruction of the Xindi superweapon by the crew of Enterprise in 2154, Commander Tucker, and Ensign Mayweather found themselves over what was apparently WWII-era San Francisco, being attacked by P-51 Mustangs, while Captain Archer was seen lying unconscious in a field hospital – under the observation of a member of a previously-unknown alien in a Nazi general's uniform. The Enterprise destroyed Vosk's time machine near the Brooklyn Bridge, thus closing this timeline and apparently preventing a major temporal war. This was one of the major campaigns of the Temporal Cold War. 

World War II and the Guardian of Forever
An alternate timeline also exists in which Germany won the war due to the delayed entry into the war by the United States. This was caused by the prevention of Edith Keeler's death by Doctor Leonard McCoy, who had traveled to the past from the 23rd century. Keeler was an anti-war activist, whose activism had persuaded the United States to stay out of the war long enough to ensure a Nazi victory. This errant timeline was repaired by James T. Kirk and Spock.

In the altered reality, Edith eventually met with President Roosevelt, effectively organizing pacifist movements to ensure that the United States did not join the Allied Powers and contribute to the escalation of war. Without the US's help fighting them, Germany completed its heavy-water molecular experiments, created an atomic bomb first in the new history, and used their V-2 rockets to launch them, effectively capturing the world. This timeline was averted when McCoy was followed through the Guardian of Forever time-portal, by Kirk and Spock, who prevented him from interfering in her death, restoring the 'correct' version of history. 

Background Information
A large number of Star Trek original series writers, actors, and producers served as veterans of the Second World War. Among these were Gene Roddenberry, James Doohan, DeForest Kelley, Mark Lenard, and Matt Jefferies. The exploits of the US Navy Aircraft carrier USS Enterprise inspired the name of Kirk's ship.

In, Spock states that eleven million people died in World War II. This, however, severely contradicts current data, which places the death toll anywhere from a low of twenty million (if only military is counted) to a high of over seventy million (if military and civilians are counted). Most counts settle on around fifty million or so.

Spock may have been referring solely to civilian casualties as a result of "slavery" and "despotism" rather than the total war itself. 11 million is a number frequently given for civilian deaths solely from Nazi policies. This might explain the six million figure he gave for World War I, too, as that is about an average (slightly on the low side) estimate of civilian deaths out of a World War I total of about sixteen million.

World War II was mentioned in the shooting script of. In the scene, Miles O'Brien talks to Kira Nerys about his new holoprogram based on the Battle of Britain. Major Kira was not familiar with the war.

According to the novella Age of the Empress, the Second World War also occurred in the mirror universe, with Japan as one as its participants. One of the results appears to have been a lessening of the power of Japan's emperor, as the Kyoto Imperial Palace was turned into a tourist attraction.