World War I

Clockwise from the top: The aftermath of shelling during the Battle of the Somme, Mark V tanks cross the Hindenburg Line, HMS Irresistible sinks after hitting a mine in the Dardanelles, a British Vickers machine gun crew wears gas masks during the Battle of the Somme, Albatros D.III fighters of Jagdstaffel 11

Date	28 July 1914 – 11 November 1918 (4 years, 3 months and 2 weeks) Peace treaties Treaty of Versailles Signed 28 June 1919 (4 years and 11 months) Treaty of Saint-Germain-en-Laye Signed 10 September 1919 (5 years, 1 month, 1 week and 6 days) Treaty of Neuilly-sur-Seine Signed 27 November 1919 (4 years, 1 month, 1 week and 6 days) Treaty of Trianon Signed 4 June 1920 (5 years, 10 months and 1 week) Treaty of Sèvres Signed 10 August 1920 (6 years, 1 week and 6 days) United States–Austria Peace Treaty Signed 24 August 1921 (3 years, 8 months, 2 weeks and 3 days) United States–Germany Peace Treaty Signed 25 August 1921 (4 years, 4 months, 2 weeks and 5 days) United States–Hungary Peace Treaty Signed 29 August 1921 (3 years, 8 months, 3 weeks and 1 day) Treaty of Lausanne Signed 24 July 1923 (8 years, 8 months, 3 weeks and 4 days)
Location	Europe, Africa, the Middle East, the Pacific Islands, China, Indian Ocean, and off the coast of South and North America
Result	Allied victory End of the German, Russian, Ottoman, and Austro-Hungarian empires Formation of new countries in Europe and the Middle East Transfer of German colonies and regions of the former Ottoman Empire to other powers Establishment of the League of Nations. (more...)

Belligerents

Allied Powers
France
British Empire
Russia (1914–17)
Serbia
Montenegro
Belgium
Japan
Italy (1915–18)
Portugal (1916–18)
Romania (1916–18)
Hejaz (1916–18)
United States (1917–18)
Greece (1917–18)
Siam (1917–18)

...and others

Central Powers
Germany
Austria-Hungary
Ottoman Empire
Bulgaria (1915–18)

...and co-belligerents

Commanders and leaders

Allied leaders
Georges Clemenceau
Raymond Poincaré
H. H. Asquith
David Lloyd George
Vittorio Orlando
Victor Emmanuel III
Woodrow Wilson
Yoshihito
Nicholas II
Peter I
Ferdinand I

...and others

Central Powers leaders
Wilhelm II
Franz Joseph I †
Karl I
Mehmed V
Three Pashas
Ferdinand I

...and others

Strength

12,000,000
8,841,541
8,660,000
5,615,140
4,743,826
1,234,000
800,000
707,343
380,000
250,000
50,000

Total: 42,959,850

13,250,000
7,800,000
2,998,321
1,200,000

Total: 25,248,321

Casualties and losses

Military dead:
5,525,000
Military wounded:
12,831,500
Military missing:
4,121,000
Total:
22,477,500 KIA, WIA or MIA
...further details.

Military dead:
4,386,000
Military wounded:
8,388,000
Military missing:
3,629,000
Total:
16,403,000 KIA, WIA or MIA
...further details.

...
Wikipedia