War Entry Dates, Axis and Allies

 

Against the Allies
  Entry End Years Months Days Total Combat
Germany 1 September, 1939 8 May, 1945 5 8 8 2,077 Y
Italy 1 June, 1940 8 September, 1943 3 3 8 1,195 Y
Hungary 10 April, 1941 20 January, 1945 3 9 11 1,382 Y
Bulgaria 24 April, 1941 8 September, 1944 3 4 16 1,234 Y
Romania 22 June, 1941 24 August, 1944 3 2 3 1,160 Y
Finland 25 June, 1941 15 September, 1944 3 2 22 1,179 Y
Slovakia 1 December, 1941 4 April, 1945 3 4 4 1,221 Y
Japan 7 December, 1941 15 August, 1945 3 8 9 1,348 Y
Croatia 14 December, 1941 8 May, 1945 3 4 25 1,242 Y
Albania 17 December, 1941 29 November, 1944 2 11 13 1,079 Y
Thailand 25 January, 1942 15 August, 1945 3 6 22 1,299 Y

 

Against the Axis
  Entry End Years Months Days Total Combat
Poland 1 September, 1939 27 September, 1939 - - 28 28 Y
France 3 September, 1939 25 June, 1940 - 9 23 297 Y
United Kingdom 3 September, 1939 15 August, 1945 5 11 13 2,174 Y
Australia 3 September, 1939 15 August, 1945 5 11 13 2,174 Y
India 3 September, 1939 15 August, 1945 5 11 13 2,174 Y
New Zealand 3 September, 1939 15 August, 1945 5 11 13 2,174 Y
South Africa 3 September, 1939 15 August, 1945 5 11 13 2,174 Y
Canada 10 September, 1939 15 August, 1945 5 11 6 2,167 Y
Denmark 9 April, 1940 9 April, 1940 - - 1 1 Y
Norway 9 April, 1940 10 June, 1940 - 2 2 63 Y
Belgium 10 May, 1940 28 May, 1940 - - 19 19 Y
Luxembourg 10 May, 1940 10 May, 1940 - - 1 1 Y
Netherlands 10 May, 1940 14 May, 1940 - - 5 5 Y
Greece 28 October, 1940 1 June, 1941 - 7 5 217 Y
Yugoslavia 6 April, 1941 17 April, 1941 - - 12 12 Y
U.S.S.R. 22 June, 1941 15 August, 1945 4 1 25 1,516 Y
United States 7 December, 1941 15 August, 1945 3 8 9 1,348 Y
Panama 7 December, 1941 15 August, 1945 3 8 9 1,348 -
Costa Rica 8 December, 1941 15 August, 1945 3 8 8 1,347 -
Dominican Republic 8 December, 1941 15 August, 1945 3 8 8 1,347 -
Guatemala 8 December, 1941 15 August, 1945 3 8 8 1,347 -
Honduras 8 December, 1941 15 August, 1945 3 8 8 1,347 -
Nicaragua 8 December, 1941 15 August, 1945 3 8 8 1,347 -
Philippines 8 December, 1941 15 August, 1945 3 8 8 1,347 Y
China 9 December, 1941 15 August, 1945 3 8 7 1,346 Y
Brazil 2 May, 1942 15 August, 1945 3 3 14 1,202 Y
Mexico 22 May, 1942 15 August, 1945 3 2 25 1,182 Y
Ethiopia 14 December, 1942 15 August, 1945 2 8 2 976 -
Iraq 16 January, 1943 15 August, 1945 2 7 0 943 -
Bolivia 7 April, 1943 15 August, 1945 2 4 9 862 -
Iran 9 September, 1943 8 May, 1945 1 8 0 608 -
Italy 13 October, 1943 8 May, 1945 1 6 26 574 Y
Colombia 26 November, 1943 8 May, 1945 1 5 13 530 -
Liberia 27 January, 1944 15 August, 1945 1 6 20 567 -
Romania 24 August, 1944 8 May, 1945 - 8 15 258 Y
Bulgaria 8 September, 1944 8 May, 1945 - 8 1 243 Y
France (Provisional) 9 September, 1944 8 May, 1945 - 8 0 242 Y
Finland 15 September, 1944 8 May, 1945 - 7 24 236 Y
Hungary 20 January, 1945 8 May, 1945 - 3 19 109 Y
Ecuador 2 February, 1945 15 August, 1945 - 6 14 195 -
Paraguay 8 February, 1945 15 August, 1945 - 6 8 189 -
Peru 11 February, 1945 15 August, 1945 - 6 5 186 -
Chile 12 February, 1945 15 August, 1945 - 6 4 185 -
Venezuela 14 February, 1945 15 August, 1945 - 6 2 183 -
Uruguay 22 February, 1945 15 August, 1945 - 5 25 175 -
Turkey 23 February, 1945 15 August, 1945 - 5 24 174 -
Egypt 24 February, 1945 15 August, 1945 - 5 23 173 -
Syria 26 February, 1945 15 August, 1945 - 5 21 171 -
Lebanon 27 February, 1945 15 August, 1945 - 5 20 170 -
Saudi Arabia 1 March, 1945 15 August, 1945 - 5 18 168 -
Argentina 27 March, 1945 15 August, 1945 - 4 20 142 -
Mongolia 9 August, 1945 15 August, 1945 - - 7 7 Y

 

Notes:

(1) Total days count includes end date.

(2) China began fighting Japanese on 7 July, 1937 (8 years, 1 month, 9 days; 2,962 total days).

(3) Italy, Finland, Romania, Bulgaria and Hungary switched sides between 1943-45.

(4) Total days count ignores breaks in conflict such as U.S.S.R. between V-E Day and entry into war against Japan (8/5/45 - 9/8/45). Numerous countries that had declared war on Germany did not declare war against Japan until after V-E Day, this break is also ignored.

(5) For countries occupied by Germany in 1939-41, end date is date of initial surrender even though many of them contributed "free" troops which continued fighting for Allies until V-E Day. French Provisional Government (GPRF) is included as it represents re-establishment of French government in its own territory.

Source: Adapated from Wikipedia; The World At War