Animated map of the European theatre of war during WWII

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.

List of war declarations

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.

Key to type (fourth column):
A Attack without prior, formal declaration of war;
C Declaration and/or attack without standard, formal procedure, sometimes preceded by a casus belli thus fait accompli;
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
Date Initiator nation(s) Targeted nation(s) Type Notes/comments Document/event
1939-09-01 Nazi Germany Germany Poland A German attack began at 4:44 a.m., Berlin and Warsaw time.[2][3][4] Invasion
1939-09-01  Slovakia Poland A Invasion
1939-09-03  United Kingdom
 Australia
 New Zealand
 India
Tonga
Jordan Transjordan
Nazi Germany Germany U[3][5] At 11:15 a.m. London time,[6] British PM, Neville Chamberlain publicly delivered his Ultimatum Speech.[a][5][7] As the Statute of Westminster 1931 was not yet ratified by the parliaments of Australia and New Zealand, the British declaration of war on Germany also applied to those dominions. Tonga was not a British dominion, instead, as part of the British Commonwealth (a protected state of the UK and the British Empire) declared war separately, alongside Britain (since it administers their foreign affairs).[8] United Kingdom declaration
1939-09-03 France

Morocco
Tunisia

Nazi Germany Germany U The French ultimatum to Germany expired a few hours after the British ultimatum, at 17:00. French declaration
1939-09-04 Nepal Nepal Nazi Germany Germany W

Declaration

1939-09-06 South Africa Nazi Germany Germany W[3][5] Declaration
1939-09-10 Bahrain
 Canada
Oman
Nazi Germany Germany W[3][5] Canada's declaration several days after that of the United Kingdom is seen as a watershed moment in Canadian home rule and sovereignty.

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

Declaration

Declaration

Declaration

1939-09-17  Soviet Union Poland A[3][5] Invasion
1939-11-09 Kuwait Kuwait Nazi Germany Germany W Kuwaiti Declaration of War
1939-11-30  Soviet Union  Finland A[3][5] Second war between these nations (after Finnish invasion in 1918–1920). Invasion
1940-04-09 Nazi Germany Germany  Denmark
 Norway
A[3] Invasion of Denmark
Invasion of Norway
1940-04-12 United Kingdom  Faroe Islands A[5] Invasion
1940-05-10 Nazi Germany Germany  Belgium
 Netherlands
A/W[3][5] Date of the German offensive in the West, W from Belgium and the Netherlands.[9]

Belgium

Netherlands

1940-05-10 Nazi Germany Germany  Luxembourg A[5] Luxembourg
1940-05-10  United Kingdom Iceland Iceland A Invasion
1940-06-10 Italy France
 United Kingdom
W[3][5] France and the UK
1940-06-10  Canada Italy W[3] Declaration
1940-06-11 South Africa
 Australia
 New Zealand
France
Italy W[3]

South Africa

Australia

New Zealand

France

1940-07-03  United Kingdom Vichy France A Vichy France cuts off diplomatic relations with the United Kingdom on 8 July 1940. Attack
1940-09-09 Italy Egypt A Egypt never formally declared war on Italy. Invasion
1940-09-22  Japan Vichy France A Japanese troops occupy French Indochina Invasion
1940-09-23 Free France
 United Kingdom
 Australia
Vichy France A Invasion
1940-10-??  Thailand Vichy France A Franco-Thai War
1940-10-28  Italy Greece U[5] Italy invades Greece Invasion
1940-11-23 Belgium (in-exile)  Italy W[10] Declaration
1941-02-05 Free France Italy A Invasion
1941-04-06 Nazi Germany Germany Greece W[3][5] Invasion
1941-04-06 Nazi Germany Germany
Italy
Yugoslavia A[3][5] Invasion
1941-04-07 Yugoslavia Hungary A[11] After the German invasion, bombing of Hungarian locations Invasion
1941-04-14 Nazi Germany Germany Egypt A Egypt did not formally declare war until 1945. Invasion
1941-05-02 United Kingdom Iraq A Invasion
1941-06-08 Free France Nazi Germany Germany A [citation needed] Invasion
1941-06-22 Nazi Germany Germany
Italy
 Soviet Union W[5] A timed declaration of war was given by Germany at the time of the attack[12] Invasion
1941-06-22/24 Romania  Soviet Union A On June 22, Romanian leader Ion Antonescu declared a "holy war" to reclaim ancestral lands and against Bolshevism in an appeal to the nation.[13] The Romanian army began limited military operations. On June 24, Romania officially declared war on the Soviet Union.[13]
1941-06-22
Tuva
Nazi Germany Germany W Tuva was a client state of the Soviet Union. Part of the USSR from 1944.
1941-06-24 Bulgaria Greece
Yugoslavia
A[5] Bulgaria declares war on Greece and Yugoslavia.
1941-06-25  Finland  Soviet Union W Finland recognized a state of war with the Soviet Union; third war between these nations. Continuation War
1941-06-27 Hungary  Soviet Union C[11] After the bombing of several Hungarian locations, the Hungarian military concluded a Soviet attack, the Government had decided the two countries were already belligerent, without the consent of the Parliament, in absence of the Regent Invasion
1941-08-25  Soviet Union
 United Kingdom
 Australia
Iran A Invasion
1941-12-05  United Kingdom  Finland
Romania
Hungary
W[14] Declaration
1941-12-06  Finland
Romania
 United Kingdom W[5] Declaration
1941-12-07  United Kingdom Hungary W[15] UK declaration of war from 1941-12-05 entered into force on 1941-12-07 1 minute after midnight Declaration
1941-12-07  Japan  United States
 United Kingdom
 Thailand
A A formal message breaking off diplomatic talks was sent before but arrived after the attacks began, but this was not a declaration of war.[16] See Attack on Pearl Harbor § Japanese declaration of war

Declaration published after:

1941-12-07  Canada
 Australia
 New Zealand
 Finland
Romania
Hungary
W[5] Declaration
1941-12-07  Canada
 Panama
Yugoslavia (in-exile)
 Japan W[5] Declaration
1941-12-08  United Kingdom
 United States
 Canada
 Australia
 Costa Rica
 Dominican Republic
 El Salvador
Free France
 Guatemala

Greece (in-exile)
Haiti Haiti
 Honduras
Netherlands (in-exile)
 New Zealand
 Nicaragua
 Philippines
Tonga[8]

 Japan W[5] After the attack on Pearl Harbor, many countries declared a formal state of war on Japan

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

1941-12-08 South Africa  Japan
 Finland
Romania
Hungary
W[5] South African declaration
1941-12-08 Mongolia Mongolia Nazi Germany Germany W[citation needed]

Mongolian declaration

1941-12-08 Manchukuo Manchukuo  United States W[5]

Manchukuo declaration

1941-12-08  Japan United Kingdom British Malaya A Invasion of Malaya

Attack on Singapore

1941-12-09 Cuba Cuba  Japan W[5]
1941-12-09  China Nazi Germany Germany
Italy
 Japan
W[5] China and Japan had been at undeclared war since 1937 Second Sino-Japanese war

Declaration

1941-12-11 Nazi Germany Germany
Italy
 United States W[3][5]

German declaration

Italian declaration

1941-12-11  United States
Cuba Cuba
 Costa Rica
 Dominican Republic
 Guatemala
 Nicaragua
Nazi Germany Germany
Italy
W[5] Germany

Italy

1941-12-11 Netherlands (in-exile) Italy W[5] Declaration
1941-12-11 Poland (in-exile)  Japan W[3] Japan rejected declaration of War. Prime Minister Hideki Tōjō's answer was: "We don't accept the Polish declaration of war. The Poles, fighting for their freedom, declared war under the British pressure"[citation needed].
1941-12-12 Romania
Bulgaria
 Slovakia
 United States
 United Kingdom
W[5]

Romanian declaration

Bulgarian declaration

1941-12-12 Haiti Haiti
 El Salvador
 Panama
Nazi Germany Germany
Italy
W[5] Declaration
1941-12-12  Australia
 Netherlands
Portugal A Portugal maintained neutrality throughout World War II.

Invasion

1941-12-13  United Kingdom
 New Zealand
South Africa
Bulgaria W[5]

British declaration

New Zealand's declaration

South African declaration

1941-12-13  Honduras Nazi Germany Germany
Italy
W[5] Declaration
1941-12-13 Italy Cuba Cuba
 Guatemala
W[5] Declaration
1941-12-14 Independent State of Croatia  United States
 United Kingdom
W[5] Declaration
1941-12-15 Hungary  United States C[17] The Prime Minister informed the U.S. ambassador without approval of the Parliament and the Regent, but initially denied it would mean "war" in fact, however two days later he declared it means the two countries became belligerent. As the ambassador refused to accept the verbal form of this act, the next day the Prime Minister in written reinforced it. Declaration
1941-12-16 Czechoslovakia (in-exile) Nazi Germany Germany
Italy
 Finland
Romania
Hungary
Japan
Bulgaria
Independent State of Croatia
 Slovakia
W[5] Czechoslovakia declares war on all countries at war with the United States of America, Great Britain and the Union of Soviet Socialist Republics. Declaration
1941-12-16 Japan Raj of Sarawak Sarawak
North Borneo North Borneo
Brunei Brunei
A Invasion
1941-12-17 Albania  United States W Declaration
1941-12-19  Nicaragua Romania
Hungary
Bulgaria
W[5] Declaration
1941-12-19 Romania  Nicaragua W[18] Out of the Axis countries only Romania reciprocated, declaring war on Nicaragua on the same day Declaration
1941-12-20 Belgium (in-exile)  Japan W Declaration
1941-12-24 Haiti Haiti Romania
Hungary
Bulgaria
W[5] Declaration
1941-12-24 Romania Haiti Haiti W[19] Out of the Axis countries only Romania reciprocated, declaring war on Haiti on the same day Declaration
1941-12-25 Greece (in-exile)

 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  Thailand  United Kingdom
 United States
A Declaration
1942-01-25  United Kingdom
 New Zealand
South Africa
 Thailand W

British declaration

New Zealand's declaration

South African declaration

1942-02-19  Japan Portugal A Portugal maintained neutrality throughout World War II. Invasion
1942-03-02  Australia  Thailand W[5]

Australian declaration

1942-05-05 South Africa
Netherlands (in-exile)
Poland
Vichy France A Invasion
1942-05-05 United Kingdom
Northern Rhodesia
Southern Rhodesia
South Africa
Tanganyika Territory Tanganyika
Belgian Congo
Poland (in-exile)
Vichy France
 Japan
A Invasion
1942-05-22  Mexico Nazi Germany Germany
Italy
 Japan
W[5] Declaration
1942-06-05  United States Hungary
Romania
Bulgaria
W[11] United States Declaration of War upon Hungary
United States Declaration of War upon Romania
United States declaration of war upon Bulgaria
1942-06-13 Iroquois Iroquois Confederacy Nazi Germany Germany
Italy
 Japan
W Having never made peace with Germany from the First World War, Haudenosaunee became the only Native American state to officially declare war on the Axis powers separately from the United States (other Native American nations issued declarations or declared war de facto alongside the United States as their tribal citizens enlisted in the Armed Forces[20]).
1942-08-22 Brazil Brazil Nazi Germany Germany
Italy
W Declaration
1942-11-08 United States
Canada
Vichy France A Invasion
1942-11-10 Nazi Germany Germany
Italy
Vichy France A Invasion
1942-11-12 Nazi Germany Germany Tunisia A German invasion via airlifting several divisions in reaction to Operation Torch, swiftly occupying Tunis and the eastern part of the country, and capturing the western portions after French Tunisian resistance before the allies reached the Tunisian border. In the resulting Tunisian campaign, the Allies finally defeated the Axis forces in Africa. Invasion
1942-12-14 Ethiopia Ethiopia Nazi Germany Germany
Italy
 Japan
W On 3 October 1935, Italy invaded Ethiopia 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. Second Italo-Ethiopian War

Declaration

1943-01-09 Reorganized National Government of China  United States
 United Kingdom
W[5] Declaration
1943-01-17 Iraq Nazi Germany Germany
Italy
 Japan
W[5] Declaration
1943-01-20  Chile Nazi Germany Germany
Italy
W Chile cuts off diplomatic relations with the German Reich and the Kingdom of Italy on 20 January 1943. Declaration
1943-04-07  Bolivia Nazi Germany Germany
Italy
 Japan
Other axis nations
W Bolivia officially joined the Allies on 7 April 1943. Shortly after war was declared, the President, Enrique Peñaranda, was overthrown in a coup. Bolivian mines supplied needed tin to the Allies, but no troops or warplanes were sent overseas. Bolivians remained confident their geographic isolation would protect them from the war. Declaration
1943-08-01 State of Burma  United States
 United Kingdom
W[5] Declaration
1943-09-08 Nazi Germany Germany Italy
Albania
A After Italy's capitulation to the Allied powers, Germany swiftly invaded both Italy and Italian-controlled territories (such as Albania, an Italian satellite state) to preempt a possible Allied intervention. Operation Achse, German occupation of Albania
1943-09-09 Iran Nazi Germany Germany W Declaration
1943-10-13 Italy Nazi Germany Germany W[3] Italy had changed sides after the fall of Mussolini. The Declaration of War was given by Pietro Badoglio to the German ambassador in Madrid.[3] Declaration
1943-11-26 Colombia Nazi Germany Germany W See Colombia during World War II Declaration
1944-01-17 Free France Italian Social Republic A Invasion
1944-01-27 Liberia Nazi Germany Germany
 Japan
W Declaration
1944-06-06 France Nazi Germany Germany A Invasion
1944-07-25 France  Japan A Invasion
1944-08-25 Romania Nazi Germany Germany W[5] Romania switched sides Declaration
1944-09-05  Soviet Union Bulgaria W Declaration
1944-09-07 Hungary Romania W[5] Declaration
1944-09-07 Romania Hungary W[5] Declaration
1944-09-08 Bulgaria Nazi Germany Germany W Bulgaria switched sides Declaration
1944-09-15 Nazi Germany Germany  Finland A Lapland War
1944-09-21  San Marino Nazi Germany Germany
Italian Social Republic Italian Social Republic
W[21] Battle of San Marino
1944-09-23  Second Philippine Republic  United States
 United Kingdom
W[22] Philippine declaration
1944-12-28  Hungary  Germany W[23] The Provisional National Government, which had been established under Soviet protection in the city of Debrecen, declared war on Germany. The German-backed Arrow Cross regime was still at war with the Soviet Union and its troops were still in action. As it had not switched sides of its own accord, Hungary was never recognized as having defected to the Allies. Hungarian declaration
1945-02-02  Ecuador Nazi Germany Germany
 Japan
W Ecuadorian declaration
1945-02-07  Paraguay Nazi Germany Germany
 Japan
W Paraguayan declaration
1945-02-12  Peru Nazi Germany Germany
 Japan
W[5] Declaration
1945-02-15 Venezuela Venezuela
 Uruguay
Nazi Germany Germany
 Japan
W

Venezuelan declaration

Uruguayan declaration

1945-02-23  Turkey Nazi Germany Germany
 Japan
W Declaration
1945-02-24 Egypt Nazi Germany Germany
 Japan
W Declaration
1945-02-26 Syria
 Lebanon
Nazi Germany Germany
 Japan
W Declaration
1945-02-28  Saudi Arabia Nazi Germany Germany W Declaration
1945-03-01  Saudi Arabia  Japan W[5] Declaration
1945-03-01 Iran  Japan W[5] Iran declares war on Japan retroactive to the previous day (Feb. 28, 1945) Declaration
1945-03-03  Finland Nazi Germany Germany W Finland declares war on Germany retroactive to Sept. 15, 1944 following terms of 1944 Moscow Armistice Lapland War
1945-03-07 Romania  Japan W[5] Declaration
1945-03-27  Argentina Nazi Germany Germany
 Japan
W

Argentinean declaration

1945-04-11  Chile  Japan W Declaration
1945-06-07 Brazil Brazil  Japan W[5] Declaration
1945-07-09 Norway Norway (in-exile)  Japan W Norwegian government-in-exile announces that it had declared war on Japan on December 7, 1941 Declaration[24]
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. Soviet–Japanese War
1945-08-10 Mongolia Mongolia  Japan W[25] W (de jure) A (de facto 1945-08-09) War declared 24 hours after crossing the border with Soviet troops

Soviet Invasion of Manchuria Mongolia in World War II

1945-08-15 Viet Minh  Japan W Viet Minh declared of war on Japanese government in Indochina on August Revolution Vietnamese famine of 1945, Birth of the Viet Minh

Gallery

See also

Notes

  1. ^ 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..."

References

  1. ^ On the Opening of Hostilities; 1907; Yale Law School Library; retrieved March 2014.
  2. ^ "Germans invade Poland". History.com. Retrieved 1 December 2019.
  3. ^ a b c d e f g h i j k l m n o p q r "2194 Days of War"; (1977); Salmaggi, C. & Pallasvini, A.; ISBN 91-582-0426-1; per tables included. [Italian; American]
  4. ^ "BBC ON THIS DAY | 1". news.bbc.co.uk.
  5. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao ap aq ar as at au av Doody, Richard, "Chronology of World War II Diplomacy 1939 - 1945", World at War, archived from the original on May 5, 2016
  6. ^ Mann, Andrea. "September 3, 1939: Britain declares war on Germany after Hitler's troops invade Poland". BT.com. Retrieved 1 December 2019.
  7. ^ 1939: Britain and France declare war on Germany, BBC
  8. ^ a b "The United States Invasion of Tonga In 1942". Archived from the original on 25 February 2005. Retrieved 23 July 2021.
  9. ^ Swedish Encyklopedia; "Bonniers Lexikon" (Vol. 1); (c.1960s); table in article by Andra Världskriget: The Second World War; Pp. 461-462.
  10. ^ Veranneman, Jean-Michel (30 September 2014). Belgium in WWII. Pen and Sword. ISBN 9781783376070.
  11. ^ a b c "Táblázat az egyes államok hadiállapotba kerüléséről". arcanum.hu. Arcanum Adatbázis Kft.
  12. ^ "The Rise and Fall of the Third Reich"; Shirer, William L
  13. ^ a b Boog et al. 1998, p. 408.
  14. ^ "BBC - WW2 People's War - Timeline". www.bbc.co.uk.
  15. ^ "Hadiállapot Magyarország és Nagy-Britannia között". arcanum.hu. Arcanum Adatbázis Kft.
  16. ^ Prange, Goldstein & Dillon 1981, p. 485. "[The] fourteenth part was not a formal declaration of war. It did not even rupture diplomatic relations. It merely broke off the discussions."
  17. ^ Draveczki-Ury, Ádám (11 December 2011). "Hetven éve történt: hadüzenet az Egyesült Államoknak". honvedelem.hu. Honvédelmi Minisztérium. Archived from the original on 29 September 2019. Retrieved 23 April 2020.
  18. ^ Dr Erik Goldstein, Routledge, 2005, Wars and Peace Treaties: 1816 to 1991, p. 218
  19. ^ Dr Erik Goldstein, Routledge, 2005, Wars and Peace Treaties: 1816 to 1991, p. 217
  20. ^ Morgan, Thomas D. (Fall 1995). "Native Americans in World War II". Army History: The Professional Bulletin of Army History (35): 22–27. Archived from the original on 2017-03-27. Retrieved 2013-04-17 – via www.shsu.edu.
  21. ^ "A Timeline of Diplomatic Ruptures, Unannounced Invasions, Declarations of War, Armistices and Surrenders". WorldAtWar. Retrieved 2009-08-12.
  22. ^ "1. United States/Philippines (1898-1946)".
  23. ^ "Az új államiság kiépítése Magyarországon | Magyarok a II. világháborúban | Kézikönyvtár". www.arcanum.hu. Retrieved 2021-04-01.
  24. ^ "Norway Declares War on Japan". Canberra Times (Act : 1926 - 1995). 9 July 1945. p. 1.
  25. ^ 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.

Bibliography