Declarations of war during World War II

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 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 Diplomatic history of World War II.

List of war declarationsEdit

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   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
  Tonga
  Transjordan
  Morocco
  Tunisia
  Germany U[2][3] At 11:15 a.m. London time,[6] British PM, Neville Chamberlain publicly delivered his Ultimatum Speech.[3][a]>[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, but declared war separately, alongside Britain.[8] The French ultimatum to Germany expired a few hours later at 17:00. United Kingdom declaration
French declaration
1939-09-04   Nepal   Germany W

Declaration

1939-09-06   South Africa   Germany W[2][3] Declaration
1939-09-10   Bahrain
  Canada
  Oman
  Germany W[2][3] Declaration

Declaration

Declaration

1939-09-17   Soviet Union   Poland A[2][3] Invasion
1939-11-09   Kuwait   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   Germany   Denmark
  Norway
A[2] Invasion of Denmark
Invasion of Norway
1940-04-12   United Kingdom   Faroe Islands A[3] Invasion
1940-05-10   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   Germany   Luxembourg A[3] Luxembourg
1940-05-10   United Kingdom   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 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[3] 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   Germany   Greece W[2][3] Invasion
1941-04-06   Germany   Yugoslavia A[2][3] Invasion
1941-04-06   Italy   Yugoslavia A[3] Invasion
1941-04-07   Yugoslavia   Hungary A[11] After the German invasion, bombing of Hungarian locations Invasion
1941-04-14   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   Germany A [citation needed] Invasion
1941-06-22   Germany
  Italy
  Romania
  Soviet Union A[2][3] A timed-declaration of war was given by Germany at the time of the attack[12] Invasion
1941-06-22  
Tuva
  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[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[13] Declaration
1941-12-06   Finland
  Romania
  United Kingdom W[3] Declaration
1941-12-07   United Kingdom   Hungary W[14] 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
W/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

Invasion of Thailand

1941-12-07   Canada
  Australia
  New Zealand
  Finland
  Romania
  Hungary
W[3] Declaration
1941-12-07   Canada
  Panama
  Japan W[3] Declaration
1941-12-08   United Kingdom
  United States
  Australia
  Costa Rica
  Dominican Republic
  El Salvador
  Guatemala
  Haiti
  Honduras
  Netherlands (in-exile)
  New Zealand
  Nicaragua
  Philippines
  Tonga[8]
  Japan W[3]

British declaration
United States 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[3] South African declaration
1941-12-08   Mongolia   Germany W[citation needed]

Mongolian declaration

1941-12-08   Manchukuo   United States W[3]

Manchukuo declaration

1941-12-09   Australia
  New Zealand
  Cuba
  Japan W[3]

Australian declaration

New Zealand's declaration

1941-12-09   China   Germany
  Italy
  Japan
W[3] China and Japan had been at undeclared war since 1937 Second Sino-Japanese war

Declaration

1941-12-11   Germany
  Italy
  United States W[2][3]

German declaration

Italian declaration

1941-12-11   United States
  Cuba
  Costa Rica
  Dominican Republic
  Guatemala
  Nicaragua
  Germany
  Italy
W[3] Germany

Italy

1941-12-11   Netherlands (in-exile)   Italy W[3] Declaration
1941-12-11   Poland (in-exile)   Japan W[2] 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
  Slovak Republic
  United States
  United Kingdom
W[3]

Romanian declaration

Bulgarian declaration

1941-12-12   Haiti
  El Salvador
  Panama
  Germany
  Italy
W[3] 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

1941-12-13   Honduras   Germany
  Italy
W[3] Declaration
1941-12-13   Italy   Cuba
  Guatemala
W[3] Declaration
1941-12-14   Independent State of Croatia   United States
  United Kingdom
W[3] Declaration
1941-12-15   Hungary   United States C[15] 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)   Germany
  Italy
  Finland
  Romania
  Hungary
  Japan
  Bulgaria
  Independent State of Croatia
  Slovak Republic
W[3] Czechoslovakia declares war on all countries at war with the United States of America, Great Britain and the Union of Soviet Socialist Republics. Declaration
1941-12-17   Albania   United States W Declaration
1941-12-19   Nicaragua   Romania
  Hungary
  Bulgaria
W[3] Declaration
1941-12-19   Romania   Nicaragua W[16] 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   Romania
  Hungary
  Bulgaria
W[3] Declaration
1941-12-24   Romania   Haiti W[17] Out of the Axis countries only Romania reciprocated, declaring war on Haiti on the same day 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
1941-03-02   Australia   Thailand W[3]

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
  Belgian Congo
  Vichy France
  Japan
A Invasion
1942-05-22   Mexico   Germany
  Italy
  Japan
W[3] 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 Confederacy   Germany
  Italy
  Japan
W Only Native American nation to have officially declared war on the Axis powers separately from the United States (other Native American nations declared war de facto alongside the United States with their tribal citizens enlisting in the Armed Forces). An Iroquois representative in full regalia announced on the steps of the U.S. Capitol by the following statement: "We represent the oldest, though smallest, democracy in the world today. It is the unanimous sentiment among Indian people that the atrocities of the Axis nations are violently repulsive to all sense of righteousness of our people, and that this merciless slaughter of mankind can no longer be tolerated. Now we do resolve that it is the sentiment of this council that the Six Nations of Indians declare 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."[18] Declaration
1942-08-22   Brazil   Germany
  Italy
W Declaration
1942-11-08   United States
  Canada
  Vichy France A Invasion
1942-11-10   Germany
  Italy
  Vichy France A Invasion
1942-11-12   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   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[3] Declaration
1943-01-17   Iraq   Germany
  Italy
  Japan
W[3] Declaration
1943-01-20   Chile   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
1943-04-07   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
1943-08-01   State of Burma   United States
  United Kingdom
W[3] Declaration
1943-09-08   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   Germany W Declaration
1943-10-13   Italy   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   Germany W See Colombia during World War II Declaration
1944-01-17   Free France   Italian Social Republic A Invasion
1944-01-27   Liberia   Germany
  Japan
W Declaration
1944-06-06
  France
  Germany A Invasion
1944-07-25
  France
  Japan A Invasion
1944-08-25   Romania   Germany W[3] Romania switched sides Declaration
1944-09-05   Soviet Union   Bulgaria W Declaration
1944-09-07   Hungary   Romania W[3] Declaration
1944-09-07   Romania   Hungary W[3] Declaration
1944-09-08   Bulgaria   Germany W Bulgaria switched sides Declaration
1944-09-15   Germany   Finland A Lapland War
1944-09-21   San Marino   Germany
  Italian Social Republic
A Battle of San Marino
1944-09-23   Second Philippine Republic   United States
  United Kingdom
W[19] Philippine declaration
1944-12-28   Hungary   Germany W[20] 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   Germany
  Japan
W Ecuadorian declaration
1945-02-07   Paraguay   Germany
  Japan
W Paraguayan declaration
1945-02-12   Peru   Germany
  Japan
W[3] Declaration
1945-02-15   Venezuela
  Uruguay
  Germany
  Japan
W

Venezuelan declaration

Uruguayan 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
1945-02-28   Saudi Arabia   Germany W Declaration
1945-03-01   Saudi Arabia   Japan W[3] Declaration
1945-03-01   Iran   Japan W[3] Iran declares war on Japan retroactive to the previous day (Feb. 28, 1945) Declaration
1945-03-03   Finland   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[3] Declaration
1945-03-27   Argentina   Germany
  Japan
W

Argentinean declaration

1945-04-11   Chile   Japan W Declaration
1945-06-07   Brazil   Japan W[3] Declaration
1945-07-09   Norway (in-exile)   Japan W Norwegian government-in-exile announces that it had declared war on Japan on December 7, 1941 Declaration[21]
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. Soviet–Japanese War
1945-08-10   Mongolia   Japan W[22] 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

GalleryEdit

See alsoEdit

NotesEdit

  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..."

ReferencesEdit

  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 "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 ac ad ae af ag ah ai aj ak al am an ao ap aq ar as at au av aw Doody, Richard, "Chronology of World War II Diplomacy 1939 - 1945", World at War, archived from the original on May 5, 2016, retrieved February 2014 Check date values in: |accessdate= (help)
  4. ^ "Germans invade Poland". History.com. Retrieved 1 Dec 2019.
  5. ^ "BBC ON THIS DAY | 1". news.bbc.co.uk.
  6. ^ Mann, Andrea. "September 3, 1939: Britain declares war on Germany after Hitler's troops invade Poland". BT.com. Retrieved 1 Dec 2019.
  7. ^ 1939: Britain and France declare war on Germany, BBC
  8. ^ a b "The United States Invasion of Tonga In 1942". 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. 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. ^ "BBC - WW2 People's War - Timeline". www.bbc.co.uk.
  14. ^ "Hadiállapot Magyarország és Nagy-Britannia között". arcanum.hu. Arcanum Adatbázis Kft.
  15. ^ Draveczki-Ury, Ádám (11 December 2011). "Hetven éve történt: hadüzenet az Egyesült Államoknak". honvedelem.hu. Honvédelmi Minisztérium.
  16. ^ Dr Erik Goldstein, Routledge, 2005, Wars and Peace Treaties: 1816 to 1991, p. 218
  17. ^ Dr Erik Goldstein, Routledge, 2005, Wars and Peace Treaties: 1816 to 1991, p. 217
  18. ^ Treuer, David (22 January 2019). The Heartbeat of Wounded Knee: Native America from 1890 to the Present. Riverhead Books.
  19. ^ "1. United States/Philippines (1898-1946)".
  20. ^ "Az új államiság kiépítése Magyarországon | Magyarok a II. világháborúban | Kézikönyvtár". www.arcanum.hu. Retrieved 2021-04-01.
  21. ^ "Norway Declares War on Japan". Canberra Times (Act : 1926 - 1995). 9 July 1945. p. 1.
  22. ^ 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.