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Declarations of war during World War II

This is a timeline of formal declaration 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 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.

Table Legend: Concerning Declaration of War:

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) Declaration of war: Type Notes/comments Document/event
1939-09-01 Nazi Germany Germany Poland U[2][3] German attack began at 4:44 a.m., Berlin and Warsaw time.[4][2][5] Invasion
1939-09-01  Slovak Republic Poland A Invasion
1939-09-03  United Kingdom
France
 Australia
 New Zealand
JordanTransjordan
Morocco
Tunisia
Nazi Germany Germany U[2][3] At 11:15 a.m. London time,[6] British PM, Neville Chamberlain publicly delivered his Ultimatum Speech.[3][7][8] 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 the following dominions. United Kingdom declaration, French declaration
1939-09-04  Nepal Nazi Germany Germany W

Declaration

1939-09-05 South Africa Nazi Germany Germany W[2][3] Declaration
1939-09-10 Bahrain
 Canada
Oman
Nazi Germany Germany W[2][3] Declaration

Declaration

Declaration

1939-09-17  Soviet Union Poland A[2][3] Invasion
1939-11-09 Kuwait Kuwait Nazi Germany Germany W Kuwaiti Declaration of War
1939-11-30  Soviet Union  Finland A[2][3] Second war between these nations (after Finnish invasion in 1918–1920). Invasion
1940-04-09 Nazi Germany Germany  Denmark
 Norway
A[2] Invasion of Denmark
Invasion of Norway
1940-04-12 United Kingdom  Faroe Islands A[3] Invasion
1940-05-10 Nazi Germany Germany  Belgium
 Netherlands
A/W[2][3] 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[3] Luxembourg
1940-05-10  United Kingdom Iceland Iceland A Invasion
1940-06-10 Italy France
 United Kingdom
W[2][3] France and the UK
1940-06-10  Canada Italy W[2] Declaration
1940-06-11 South Africa
 Australia
 New Zealand
Italy W[2]

South Africa

Australia

New Zealand

1940-06-11 France Italy W[2] Declaration
1940-06-25  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 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[3] Italy invades Greece Invasion
1941-02-05 Free France Italy A Invasion
1941-04-06 Nazi Germany Germany Greece W[2][3] Invasion
1941-04-06 Nazi Germany Germany Yugoslavia A[2][3] Invasion
1941-04-06 Italy Yugoslavia A[3] Invasion
1941-04-07 Yugoslavia Hungary A[10] 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
Romania
 Soviet Union A[2][3] A timed-declaration of war was given by Germany at the time of the attack[11] Invasion
1941-06-22 Flag of the Tuvan People's Republic (1941-1943).svg
Tuva
Nazi Germany Germany W Tuva was a client state of the Soviet Union. Part of the USSR from 1944.
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[10] 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[12] Declaration
1941-12-07  Japan  United States
 United Kingdom
A[2] W (Japanese point of view); A (British Empire and United States)

Declaration

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[3] Declaration
1941-12-07  Panama  Japan W[3] Declaration
1941-12-08  United States
 United Kingdom
 Australia
 Costa Rica
 Dominican Republic
 El Salvador
 Guatemala
 Haiti
 Honduras
 Netherlands
 New Zealand
 Nicaragua
 Philippines
 Japan W[3] United States declaration

British declaration
Australian declaration
Costa Rican declaration
Dominican Republic's declaration
Guatemalan declaration
Salvadorian declaration
Haitian declaration
Honduran declaration
Dutch declaration
New Zealand's declaration
Nicaraguan declaration
Philippine declaration

1941-12-08 South Africa  Japan W[3] South African declaration
1941-12-08 Mongolia Nazi Germany Germany W[citation needed]

Mongolian declaration

1941-12-08  United Kingdom Romania
 Finland
Hungary
W[3] Declaration
1941-12-09  Australia
 New Zealand
 Japan W[3]

Australian declaration

New Zealand's declaration

1941-12-09  China Nazi Germany Germany
Italy
 Japan
W[3] 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[2][3]

German declaration

Italian declaration

1941-12-11  United States Nazi Germany Germany
Italy
W[2] Germany

Italy

1941-12-11 Poland (in-exile)  Japan W[2] 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[3]

Romanian declaration

Bulgarian 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[3]

British declaration

New Zealand's declaration

South African declaration

1941-12-15 Hungary  United States C[13] 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 if this act, the next day the Prime Minister in written reinforced it. Declaration
1941-12-14 Independent State of Croatia  United States
 United Kingdom
W[3] Declaration
1941-12-16 Czechoslovakia (In-exile) Nazi Germany Germany
Italy
 Finland
Romania
Hungary
Japan
Bulgaria
Independent State of Croatia[14]
W Declaration
1941-12-17 Albania  United States 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
1942-01-16 Iraq Nazi Germany Germany
Italy
 Japan
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

1942-02-12  Peru Nazi Germany Germany
 Japan
W Declaration
1942-02-19  Japan Portugal A Portugal maintained neutrality throughout World War II. Invasion
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
Belgian Congo
Vichy France
 Japan
A Invasion
1942-05-22  Mexico Nazi Germany Germany
Italy
 Japan
W[3] Declaration
1942-06-05  United States Hungary
Romania
Bulgaria
W[10] Declaration
1942-06-13 Iroquois Confederacy Nazi Germany Germany
Italy
 Japan
W Only Native American tribe to have declared war on the Axis powers separately from the United States (other native nations de facto declared war with tribal citizens enlisting in the Armed Forces). Announced on the steps of the U.S. Capitol by a representative that "a state of war exists between our Confederacy of Six Nations on the one part and Germany, Italy, Japan and their allies against whom the United States has declared war, on the other part." Declaration
1942-08-22 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 serval 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 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

1943-01-20  Chile Nazi Germany Germany
Italy
W President Ríos officially suspended all trade and diplomatic relations with the Axis powers, and Chile officially joined the Allies as authorities began rooting out Nazi spies from Operation Bolivar. While only declaring war on Germany and Italy (although Chile would not declare war on Japan until 1945, it began imprisoning Japanese nationals in 1943), the American government and international press celebrated this day as Chile declaring war on the Axis. Declaration
1943-04-02  Bolivia Axis powers 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
1943-09-01 Flag of the Republic of China-Nanjing (Peace, Anti-Communism, National Construction).svg China Regime of Wang Jingwei Allied Powers W Declaration
1943-09-09 Iran Nazi Germany Germany W Declaration
1943-10-13 Italy Nazi Germany Germany W[2] Italy had changed sides after the fall of Mussolini. The Declaration of War was given by Pietro Badoglio to the German ambassador in Madrid.[2] 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
Hungary
W Romania switched sides Declaration
1944-09-05  Soviet Union Bulgaria W Declaration
1944-09-08 Bulgaria Nazi Germany Germany W Bulgaria switched sides Declaration
1944-09-15 Nazi Germany Germany  Finland A Lapland War
1944-09-23  Second Philippine Republic  United States
 United Kingdom
W[15] Philippine declaration
1945-02-02  Ecuador Nazi Germany Germany
 Japan
W Ecuadorian declaration
1945-02-07  Argentina
 Paraguay
Nazi Germany Germany
 Japan
W

Argentinean declaration

Paraguayan declaration

1945-02-15 Venezuela
 Uruguay
Nazi Germany Germany
 Japan
W

Venezuelan declaration

Uruguayan declaration

1945-02-21  San Marino Nazi Germany Germany W 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
1945-03-03  Finland Nazi Germany Germany W Finland switched sides Lapland War
1945-04-01  Saudi Arabia  Japan W Declaration
1945-04-11  Chile Japan W Declaration
1945-07-06 Brazil  Japan W Declaration
1945-07-09  Norway  Japan W Declaration[16]
1945-07-14 Italy  Japan W Declaration
1945-08-08  Soviet Union  Japan W[2] Last outbreak of war during the entire Second World War. Declaration
1945-08-10 Mongolia  Japan W[17] 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

References

  1. ^ On the Opening of Hostilities; 1907; Yale Law School Library; retrieved March 2014.
  2. ^ a b c d e f g h i j k l m n o p q r s t u v w "2194 Days of War"; (1977); Salmaggi, C. & Pallasvini, A.; ISBN 91-582-0426-1; per tables included. [Italian; American]
  3. ^ 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 Timeline Data Archived May 5, 2016, at the Wayback Machine; World at War online; retrieved February 2014.
  4. ^ "Germans invade Poland". History.com. Retrieved 1 Dec 2019.
  5. ^ On This Day
  6. ^ Mann, Andrea. "September 3, 1939: Britain declares war on Germany after Hitler's troops invade Poland". BT.com. Retrieved 1 Dec 2019.
  7. ^ 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..."
  8. ^ 1939: Britain and France declare war on Germany, BBC
  9. ^ Swedish Encyklopedia; "Bonniers Lexikon" (Vol. 1); (c.1960s); table in article by Andra Världskriget: The Second World War; Pp. 461-462.
  10. ^ a b c "Táblázat az egyes államok hadiállapotba kerüléséről". arcanum.hu. Arcanum Adatbázis Kft.
  11. ^ "The Rise and Fall of the Third Reich"; Shirer, William L
  12. ^ Declaration of War on Finland, Hungary and Romania
  13. ^ Draveczki-Ury, Ádám (11 December 2011). "Hetven éve történt: hadüzenet az Egyesült Államoknak". honvedelem.hu. Honvédelmi Minisztérium.
  14. ^ all countries at war with the United States, United Kingdom, or the Soviet Union
  15. ^ [1]
  16. ^ [trove.nla.gov.au]
  17. ^ 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.