This is a timeline of 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 the act of delivering a performative 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).[1] For the diplomatic maneuvering behind these events, which led to hostilities between nations during World War II, see 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 facto state 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.
Morocco Tunisia
Declaration
As for Bahrain, given its status as a protected state of the United Kingdom, it was technically at war as of Britain's declaration, this is an acknowledgement of the declaration of war by Britain (due to coercion by an advisor),
Oman, under British influence, is coerced to participate in the war effort
Belgium
Netherlands
South Africa
Australia
New Zealand
France
Declaration published after:
Greece (in-exile) Haiti Honduras Netherlands (in-exile) New Zealand Nicaragua Philippines Tonga[8]
British declaration United States declaration Canadian declaration Australian declaration Costa Rican declaration Dominican Republic's declaration Guatemalan declaration Salvadoran declaration Haitian declaration Honduran declaration Dutch declaration New Zealand's declaration Nicaraguan declaration Philippine declaration Tongan declaration
Mongolian declaration
Manchukuo declaration
Attack on Singapore
German declaration
Italian declaration
Italy
Romanian declaration
Bulgarian declaration
Invasion
British declaration
New Zealand's declaration
South African declaration
Japan
Australian declaration
Venezuelan declaration
Uruguayan declaration
Argentinean declaration
Soviet Invasion of Manchuria Mongolia in World War II