Animated map of the European Theater of war during WWII
This is a timeline of formal declarations of War during World War II.
A declaration of war is a formal act by which one nation goes to war against another. The declaration is usually an act of delivering a performative speech (not to be confused with a mere speech) or the presentation of a signed document by an authorized party of a national government in order to create a state of war between two or more sovereign states. The official international protocol for declaring war was defined in The Hague Peace Conference of 1907 (or Hague II). For the diplomatic maneuvering behind these events, which led to hostilities between nations during World War II, see the article entitled Diplomatic history of World War II.
Below is a table showing the outbreak of wars between nations which occurred during World War II. Indicated are the dates (during the immediate build-up to, or during the course of, World War II), from which a de factostate of war existed between nations. The table shows both the "Initiator Nation(s)" and the nation at which the aggression was aimed, or "Targeted Nation(s)". Events listed include those in which there were simple diplomatic breaking of relations that did not involve any physical attack, as well as those involving overt declarations or acts of aggression. In rare cases, war between two nations occurred twice, with an intermittent period of peace. The list here does not include peace treaties or periods of any armistice.
Table Legend: Concerning Declaration of War: A = Attack without prior, formal declaration of war; U = State of war arrived at through use of ultimatum; W = Formal declaration of war made.
Outbreaks of war between nations during World War II
Japan rejected declaration of War. Prime Minister Hideki Tōjō's answer was following: "We don't accept the Polish declaration of war. The Poles, fighting for their freedom, declared war under the British pressure".
On 3 October 1935, ItalyinvadedEthiopia without a formal declaration of war. In response to the Italian invasion, Ethiopia declared war on Italy. Most of Ethiopia was occupied by Italy in 1936, however parts of Ethiopia remained under the control of the Ethiopian Patriots Movement, which begun its guerrilla war against the occupying Italian forces the day Addis Ababa fell in May 1936. In May 1941, Addis Ababa was liberated by the Gideon Force, restoring sovereignty to Ethiopia.
British Prime Minister Neville Chamberlain, landing at Heston aerodrome on 30 September 1938 after his meeting with Hitler at Munich. In his hand he holds the peace agreement between Britain and Germany.
^Note: Included in the speech: "...This morning, the British Ambassador in Berlin handed the German Government a final note, stating that unless we heard from them by 11 O'clock that they were prepared at once to withdraw their troops from Poland a state of war would exist between us. I have to tell you now that no such undertaking has been received and that consequently this country is at war with Germany..."
^Christopher P. Atwood (1999), "Sino-Soviet Diplomacy and the Second Partition of Mongolia, 1945–1946", Mongolia in the Twentieth Century: Landlocked Cosmopolitan, Bruce A. Elleman and Stephen Kotkin, eds. (Armonk, NY: M. E. Sharpe), 147.