Editing Casus belli (section)

=== World War II ===
In [[Manchukuo|Japanese Manchuria]], Japan staged the [[Marco Polo Bridge incident|Marco Polo Bridge Incident]] in 1937 as a casus belli to initiate the Second World War. 

In his autobiography ''[[Mein Kampf]]'', [[Adolf Hitler]] had in the 1920s advocated a policy of ''[[Lebensraum]]'' ("living space") for the [[Germans|German people]], which in practical terms meant German territorial expansion into Eastern Europe.<ref>{{Cite web |date=February 23, 2023 |title=Lebenstraum {{!}} Holocaust Encyclopedia |url=https://encyclopedia.ushmm.org/content/en/article/lebensraum }}</ref>
[[File:Alfred Naujocks.jpg|thumb|[[Alfred Naujocks]], who organized and led the [[Gleiwitz incident]] on the orders of [[Heydrich]].]]
In August 1939, to implement the first phase of this policy, [[Germany]]'s [[Nazi]] government under Hitler's leadership staged the [[Gleiwitz incident]], which was used as a ''{{lang|la|casus belli}}'' for the [[invasion of Poland]] the following September. Nazi forces used [[Nazi concentration camps|concentration camp]] prisoners posing as Poles on 31 August 1939, to attack the German radio station Sender Gleiwitz in Gleiwitz, Upper [[Silesia]], Germany (since 1945: [[Gliwice]], Poland) on the eve of World War II. [[Poland]]'s allies, the [[United Kingdom|UK]] and [[France]], subsequently declared war on Germany in accordance with their alliance.{{Citation needed|date=March 2022}} The [[United States]] would declare war on [[Japan]] after the attack on [[Pearl Harbor]] on December 7, 1941.

In 1941, acting once again in accordance with the policy of Lebensraum, [[Nazi Germany]] [[Operation Barbarossa|invaded the Soviet Union]], using the ''casus belli'' of [[preemptive war]] to justify the act of aggression.{{Citation needed|date=March 2022}}