Declarations of war during World War II
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.
List of war declarations
Below is a table showing the Outbreaks 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.
W = Formal declaration of war made.
|Date||Initiator Nation(s)||Targeted Nation(s)||Declaration of War: Type||Notes/Comments||Document/Event|
|1939-09-01||Germany||Poland||A ||German attack began at 4:44 am||Invasion|
|1939-09-03||United Kingdom, France||Germany||U ||At 11 O'clock (am) British PM, Neville Chamberlain publicly delivered his Ultimatum Speech.||Document|
|1939-09-03||Australia, New Zealand||Germany||W|
|1939-11-30||Soviet Union||Finland||A||First war between these nations.||Invasion|
|1940-05-10||Germany||Belgium, Netherlands||A/W||Date of the German offensive in the West, W from Belgium and the Netherlands.|
|1940-06-10||Italy||France, United Kingdom||W||France and the UK|
|1940-06-11||South Africa, Australia, New Zealand||Italy||W|
|1940-10-28||Italy||Greece||U||Italy invades Greece||Invasion|
|1941-06-22||Germany, Italy, Romania||Soviet Union||A||A timed-declaration of war was given by Germany at the time of the attack||Invasion|
|1941-06-25||Finland||Soviet Union||W||Finland recognized a state of war with the Soviet Union; second war between these nations.||Continuation War|
|1941-12-07||United Kingdom||Romania, Hungary||U||Declaration|
|1941-12-07||Empire of Japan||United States and the British Empire||A||W (Japanese point of view); A The "Western" (Attack on Pearl Harbor);|
|1941-12-07||Canada, Australia, New Zealand||Japan, Finland, Romania, Hungary||W|
|1941-12-07||United Kingdom||Romania, Finland and Hungary||W||Declaration|
|1941-12-08||United States, United Kingdom, Australia, Costa Rica, Dominican Republic, El Salvador, Haiti, Honduras, The Netherlands, New Zealand and Nicaragua||Japan||W|
|1941-12-08||South Africa||Japan||W||South African declaration|
|1941-12-08||China||Germany, Italy, Japan||W||Declaration|
|1941-12-09||Australia, New Zealand||Japan||W|
|1941-12-11||Germany, Italy||United States||W|
|1941-12-11||United States||Germany, Italy||W||Germany|
|1941-12-11||Poland's government-in-exile||Japan||W||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".|
|1941-12-12||Romania, Bulgaria||United States, United Kingdom||W|
|1941-12-13||United Kingdom, New Zealand, South Africa||Bulgaria||W|
|1941-12-14||Croatia||United States, United Kingdom||W||Declaration|
|1941-12-16||Czechoslovak government-in-exile||all countries at war with the United States, United Kingdom, or the Soviet Union||W||Declaration|
|1941-12-19||Nicaragua||Bulgaria, Hungary and Romania||W||Declaration|
|1942-01-01||United Nations||Axis powers||W||Declared during Arcadia Conference||Declaration|
|1942-01-25||United Kingdom, New Zealand, South Africa||Thailand||W|
|1942-05-22||Mexico||Germany, Italy, Japan||W||Declaration|
|1943-10-13||Italy||Germany||W||Italy had changed side after the fall of Mussolini. The Declaration of War was given by Pietro Badoglio to the German ambassador in Madrid.||Declaration|
|1944-08-25||Romania||Germany, Hungary||W||Romania switched sides||Declaration|
|1944-09-08||Bulgaria||Germany||W||Bulgaria switched sides||Declaration|
|1945-02-07||Argentina, Paraguay||Germany, Japan||W|
|1945-02-15||Venezuela, Uruguay||Germany, Japan||W|
|1945-04-03||Finland||Germany||W||Finland switched sides||Lapland War|
|1945-08-08||Soviet Union||Japan||W||Last outbreak of war during the entire Second World War.||Declaration|
- Harman, Nicholas (1990). Dunkirk: the Necessary Myth. Jove. ISBN 978-0340517857.
- German White Book. All World Wars.
- Hitler, Adolph (2012). The Great Tragedy: Germany's Declaration of War against the United States of America. ISBN 978-1300127703.
- Torrie, Julia S. (2010). "For Their Own Good": Civilian Evacuations in Germany and France, 1939-1945. Berghahn Books. ISBN 978-1845457259.
- On the Opening of Hostilities; 1907; Yale Law School Library; retrieved March 2014.
- Note: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 armistices.
- "2194 Days of War"; (1977); Salmaggi, C. & Pallasvini, A.; ISBN 91-582-0426-1; per tables included. [Italian; American]
- Timeline Data; World at War online; retrieved February 2014.
- On This Day
- 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..."
- 1939: Britain and France declare war on Germany, BBC
- Swedish Encyklopedia; "Bonniers Lexikon" (Vol. 1); (c.1960s); table in article by Andra Världskriget: The Second World War; Pp. 461-462.
- "The Rise and Fall of the Third Reich"; Shirer, William L