Editing World war (section)

===Second World War===
{{Main|World War II}}
[[File:The British Army in the Normandy Campaign 1944 B8553.jpg|thumb|A [[British Army]] [[Churchill tank|Churchill]] tank passing a destroyed ''[[Wehrmacht]]'' [[Panzer IV]] tank during [[Operation Overlord]], part of World War II]]

The Second World War occurred from 1939 to 1945 and is the only conflict in which [[nuclear weapons]] have been used; both [[Hiroshima]] and [[Nagasaki]], in the [[Japanese Empire]], were [[Atomic bombings of Hiroshima and Nagasaki|devastated]] by atomic bombs dropped by the United States. The main Axis powers were [[Nazi Germany]], the [[Empire of Japan]], and the [[Kingdom of Italy]]; while the [[British Empire|United Kingdom]], the [[United States]], the [[Soviet Union]] and [[Republic of China (1912–1949)|China]] were the "[[Big Four (World War II)|Big Four]]" Allied powers.<ref>{{cite book|title=The Turning Point: Roosevelt, Stalin, Churchill, and Chiang Kai-Shek, 1943: The Moscow, Cairo, and Teheran Conferences|first=Keith|last=Sainsbury|location=[[Oxford]]|publisher=[[Oxford University Press]]|year=1986}}</ref> [[Nazi Germany]], led by [[Adolf Hitler]], was responsible for [[genocides]], most notably [[the Holocaust]], which murdered demographics considered [[Untermensch]] by the Nazis. These included about six million [[Jews]] and about five million others, such as [[Slavs]], [[Romani people|Roma]], [[homosexuals]], and the physically and mentally disabled.<ref>{{Cite web |title=Documenting Numbers of Victims of the Holocaust and Nazi Persecution |url=https://encyclopedia.ushmm.org/content/en/article/documenting-numbers-of-victims-of-the-holocaust-and-nazi-persecution |access-date=2020-09-05 |website=encyclopedia.ushmm.org |archive-date=2020-02-20 |archive-url=https://web.archive.org/web/20200220011124/https://encyclopedia.ushmm.org/content/en/article/documenting-numbers-of-victims-of-the-holocaust-and-nazi-persecution |url-status=live }}</ref> The [[United States]], the [[Soviet Union]], and [[Canada]] deported and [[interned]] minority groups within their own borders and, largely because of the conflict, many ethnic [[Germans]] were later expelled from [[Eastern Europe]]. Japan was responsible for attacking [[Neutral country|neutral nations]] without a [[declaration of war]], such as the [[attack on Pearl Harbor]]. It is also known for its brutal treatment and killing of Allied [[prisoners of war]] and the inhabitants of [[Asia]]. It also used Asians as [[forced laborers]] and was responsible for the [[Nanjing Massacre]] in which 250,000 civilians were brutally murdered by Japanese troops. [[Noncombatants]] suffered at least as badly as or worse than [[combatants]], and the distinction between combatants and noncombatants was often blurred by the belligerents of [[total war]] in both conflicts.<ref name="stories">{{cite web |url= https://storiespreschool.com/worldwar.html |title= World War |access-date= 11 November 2019 |archive-date= 11 November 2019 |archive-url= https://web.archive.org/web/20191111061254/https://storiespreschool.com/worldwar.html |url-status= live }}</ref>

The outcome of the war had a profound effect on the course of [[Human history|world history]]. The old European empires collapsed or they were dismantled as a direct result of the crushing costs of the war and in some cases, their fall was caused by the defeat of imperial powers. The [[United States]] became firmly established as the dominant global [[superpower]], along with its close competitor and ideological foe, the [[Soviet Union]]. The two superpowers exerted political influence over most of the world's [[Nation state|nation-states]] for decades after the end of the Second World War. The modern international security, economic, and diplomatic system was created in the aftermath of the war.<ref name="stories"/>

Institutions such as the [[United Nations]] were established to collectivize international affairs, with the explicit goal of preventing another outbreak of general war. The wars had also greatly changed the course of daily life. Technologies developed during wartime had a profound effect on peacetime life as well, such as through advances in [[jet aircraft]], [[penicillin]], [[nuclear power|nuclear energy]], and [[electronic computers]].<ref name="stories"/>