Declarations of war during World War II

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Animated map of the European Theater of war during WW 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).[1] 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.[2]

Outbreaks of Wars between Nations during World War II
Table Legend: Concerning "Declaration of War: Type." A = Attack without prior, formal declaration of war; U = State of war arrived at through use of ultimatum;
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 [3][4] German attack began at 4:44 am[3][5] Invasion
1939-09-03 United Kingdom, France Germany U [3][4] At 11 O'clock (am) British PM, Neville Chamberlain publicly delivered his Ultimatum Speech.[4][6][7] Document
1939-09-03 Australia, New Zealand Germany W[3][4]


New Zealand

1939-09-06 South Africa Germany W[3][4] Declaration
1939-09-10 Canada Germany W[3][4] Declaration
1939-09-17 Soviet Union Poland A[3][4] Invasion
1939-11-30 Soviet Union Finland A[3][4] First war between these nations. Invasion
1940-04-09 Germany Denmark, Norway A[3] Invasion
1940-05-10 Germany Belgium, Netherlands A/W[3][4] Date of the German offensive in the West, W from Belgium and the Netherlands.[8]



1940-05-10 Germany Luxembourg A[4] Luxembourg
1940-05-10 United Kingdom Iceland A Invasion
1940-06-10 Italy France, United Kingdom W[3][4] France and the UK
1940-06-10 Canada Italy W[3] Declaration
1940-06-11 South Africa, Australia, New Zealand Italy W[3]

South Africa


New Zealand

1940-06-11 France Italy [3] Declaration
1940-10-28 Italy Greece U[4] Italy invades Greece Invasion
1941-04-06 Germany Greece W[3][4] Invasion
1941-04-06 Germany, Bulgaria Yugoslavia A[3][4] Invasion
1941-04-06 Italy, Hungary Yugoslavia A[4] Invasion
1941-06-22 Germany, Italy, Romania Soviet Union A[3][4] A timed-declaration of war was given by Germany at the time of the attack[9] 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
1941-06-27 Hungary Soviet Union W[4] Invasion
1941-12-06 United Kingdom Finland U[4] Declaration
1941-12-07 United Kingdom Romania, Hungary U[4] Declaration
1941-12-07 Empire of Japan United States and the British Empire A[3] W (Japanese point of view); A The "Western" (Attack on Pearl Harbor);


Attack on Pearl Harbor

Invasion of Malaya

Attack on Singapore

Invasion of Hong Kong

1941-12-07 Canada, Australia, New Zealand Japan, Finland, Romania, Hungary W[4]



New Zealand

1941-12-07 United Kingdom Romania, Finland and Hungary W[4] Declaration
1941-12-07 Panama Japan W[4] Declaration
1941-12-08 United States, United Kingdom, Australia, Philippines, Costa Rica, Dominican Republic, El Salvador,Guatemala, Haiti, Honduras, The Netherlands, New Zealand and Nicaragua Japan,

American declaration

British declaration

Australian declaration

Cost Rican declaration

Dominican Republic's declaration

Salvadorian declaration

Haitian declaration

Honduran declaration

Dutch declaration

New Zealand's declaration

Nicaraguan declaration

Philippine declaration

1941-12-08 South Africa Japan W[4] South African declaration
1941-12-08 China Germany, Italy, Japan W[4] China and Japan had been at war since 1937 Second Sino-Japanese war


1941-12-09 Australia, New Zealand Japan W[4]

Australian declaration

New Zealand's declaration

1941-12-11 Germany, Italy United States W[3][4]

German declaration

Italian declaration

1941-12-11 United States Germany, Italy W[3] Germany


1941-12-11 Poland's government-in-exile Japan W[3] 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[4]

Romanian declaration

Bulgarian declaration

1941-12-13 United Kingdom, New Zealand, South Africa Bulgaria W[4]

British declaration

New Zealand's declaration

South African declaration

1941-12-13 Hungary United States W[4] Declaration
1941-12-14 Croatia United States, United Kingdom W[4] Declaration
1941-12-16 Czechoslovak government-in-exile all countries at war with the United States, United Kingdom, or the Soviet Union W Declaration
1941-12-17 Albania United States W Declaration
1941-12-19 Nicaragua Bulgaria, Hungary and Romania W Declaration
1941-12-20 Belgium Japan W Declaration
1942-01-01 United Nations Axis powers W Declared during Arcadia Conference Declaration
1942-01-06 Australia Bulgaria W Declaration
1942-01-25 United Kingdom, New Zealand, South Africa Thailand W

British declaration

New Zealand's declaration

South African declaration

1942-05-22 Mexico Germany, Italy, Japan W[4] Declaration
1942-08-22 Brazil Germany, Italy W Declaration
1943-04-02 Bolivia Axis members W Declaration
1943-09-09 Iran Germany W Declaration
1943-10-13 Italy Germany W[3] Italy had changed side after the fall of Mussolini. The Declaration of War was given by Pietro Badoglio to the German ambassador in Madrid.[3] Declaration
1944-08-25 Romania Germany, Hungary W Romania switched sides Declaration
1944-09-05 Soviet Union Bulgaria W Declaration
1944-09-08 Bulgaria Germany W Bulgaria switched sides Declaration
1945-02-02 Ecuador Germany, Japan W Ecuadorian declaration
1945-02-07 Argentina, Paraguay Germany, Japan W

Argentinean declaration

Paraguayan declaration

1945-02-12 Peru Germany, Japan W Declaration
1945-02-15 Venezuela, Uruguay Germany, Japan W

Venezuelan declaration

Uruguayan declaration

1945-02-21 San Marino Germany W Declaration
1945-02-23 Turkey Germany, Japan W Declaration
1945-02-24 Egypt Germany, Japan W Declaration
1945-02-26 Syria, Lebanon Germany, Japan W Declaration
1945-04-01 Saudi Arabia Japan W Declaration
1945-04-03 Finland Germany W Finland switched sides Lapland War
1945-04-11 Chile Japan W Declaration
1945-07-06 Brazil Japan W Declaration
1945-07-14 Italy Japan W Declaration
1945-08-08 Soviet Union Japan W[3] Last outbreak of war during the entire Second World War. Declaration


  • Harman, Nicholas (1990). Dunkirk: the Necessary Myth. Jove. ISBN 978-0340517857.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  • German White Book. All World Wars.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  • Hitler, Adolph (2012). The Great Tragedy: Germany's Declaration of War against the United States of America. ISBN 978-1300127703.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  • Torrie, Julia S. (2010). "For Their Own Good": Civilian Evacuations in Germany and France, 1939-1945. Berghahn Books. ISBN 978-1845457259.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>


  1. On the Opening of Hostilities; 1907; Yale Law School Library; retrieved March 2014.
  2. 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.
  3. 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 3.20 3.21 3.22 3.23 "2194 Days of War"; (1977); Salmaggi, C. & Pallasvini, A.; ISBN 91-582-0426-1; per tables included. [Italian; American]
  4. 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17 4.18 4.19 4.20 4.21 4.22 4.23 4.24 4.25 4.26 4.27 4.28 4.29 4.30 4.31 Timeline Data; World at War online; retrieved February 2014.
  5. On This Day
  6. 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..."
  7. 1939: Britain and France declare war on Germany, BBC
  8. Swedish Encyklopedia; "Bonniers Lexikon" (Vol. 1); (c.1960s); table in article by Andra Världskriget: The Second World War; Pp. 461-462.
  9. "The Rise and Fall of the Third Reich"; Shirer, William L