World War II World War II ( also known as the Second World War and abbreviated as WWII ) was the second major global conflict of the 20th century that involved various countries of Earth from the years 1939 - 1945 . History . 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 German Heinkel He 111 s and parachut ists , could be seen in the time stream as the timeline realigned itself . ( ) German chancellor Adolf Hitler , the primary aggressor in World War II , was quoted as saying , in 1938 , " " We need breathing room . " " ( ) 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 ; developments in rocketry and fission resonated on into the 24th century . ( ) While Hirogen were in control of the , one of the ship ' s holodeck s was programmed with a holographic simulation of this timeframe , set in 1944 , during an Allied invasion of Nazi - controlled territory in France . ( ) At the conclusion of the war , American General Douglas MacArthur spoke the following words : Those words were 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 . ( ) In one alternate timeline , the Na ' kuhl assisted Nazi Germany in its war effort . In this timeline , Vladimir Lenin had been assassinated in 1916 which allowed Germany to focus on its Western opponents , conquering Belgium , France and the Netherlands . The Nazis subsequently sent troops and conquered Britain , the Northeastern United States , and a part of Russia extending past Moscow as well as parts of Africa . 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 . ) Alternate timelines . Temporal Cold War . However , by 1944 this was described as Germany " stretching too far , too quickly . " Resistance fighters constantly attacked German supply lines and the front line s were too thin . An American counterattack could – and later tried to – break through the front lines , when Captain Archer and 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 weapon by the crew of " Enterprise " in 2154 , Commander Tucker and Ensign Mayweather found themselves over San Francisco , being attacked by P - 51 Mustang s , while Captain Archer was seen lying unconscious in a field hospital – under the observation of a Na ' kuhl officer in a Nazi captain ' s uniform . Near the Brooklyn Bridge , " Enterprise " destroyed a temporal conduit whose construction had been overseen by Na ' kuhl leader Vosk , thus closing this timeline and apparently preventing the 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 existed in which Germany won the Second World War , partly due to the delayed entry into the war by the United States . Another contributing factor to the German victory was 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 , in the altered timeline , had persuaded the United States to stay out of the war long enough to ensure a Nazi victory . In the altered reality , Edith Keeler eventually met with President Roosevelt , effectively organizing pacifist movements to ensure the United States did not join the Allies and contribute to the escalation of war . Without the US contributing to the efforts to fight the Axis Powers , Germany completed its heavy water molecular experiments , created an atomic bomb first in the new history , and used German V - 2 rockets to launch numerous atomic bombs , effectively capturing the world . This timeline was averted when McCoy was followed through the Guardian of Forever time portal , by James T . Kirk and Spock , who prevented him from interfering in Keeler ' s death , restoring the " correct " version of history . ( ) Appendices . Background information . A large number of TOS writers , actors , producers and other production staff members served as veterans of the Second World War . Among these were Gene Roddenberry , James Doohan , DeForest Kelley , Mark Lenard , Matt Jefferies , Robert Justman , Joseph Pevney and Ralph Senensky . The exploits of the US Navy Aircraft carrier 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 . Eleven million is a number frequently given for civilian deaths solely from Nazi policies . This might explain a figure of six million that 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 . Apocrypha . 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 .