The political and military leadership of the combatant nations of World War I varied during the course of the war. The following lists give details of who led each country and its armed forces from the point at which each nation entered the war to when hostilities ceased (largely the period August 1914 to November 1918). In addition to this, the representatives and signatories for the various armistices and peace treaties are given, as well as notes on changes made to the command structures during the war, the differences in the systems of government and upheavals such as revolutions, and indications as to who held the real political and military power.

United Kingdom

• King George V (1914-1918)
  • Prime Minister Herbert Asquith (1914-1916)
  • Prime Minister David Lloyd George (1916-1918)
    • Permutations of the War Cabinet and also the Imperial War Cabinet
      • Secretary of State for War
        • Earl Kitchener
        • David Lloyd George
        • Earl of Derby
        • Viscount Milner
• Army - Chief of the Imperial General Staff
  • General Sir Charles Douglas
  • Lieutenant-General Sir James Murray
  • General Sir Archibald Murray
  • General Sir William Robertson
  • Field-Marshal Sir Henry Wilson
• Navy - First Sea Lord
  • Prince Louis of Battenberg
  • Lord Fisher
  • Sir Henry Jackson
  • Sir John Jellicoe
  • Sir Rosslyn Wemyss
• RFC - air forces commander in the field
  • Lieutenant General Sir David Henderson
  • Major-General Sir Hugh Trenchard
• RAF - Chief of the Air Staff
  • Major-General Sir Hugh Trenchard
  • Major-General Sir Frederick Sykes

France

• President Raymond Poincaré (1914-1918)
  • Premier René Viviani (1914-1915)
  • Premier Aristide Briand (1915-1917)
  • Premier Alexandre Ribot (1917)
  • Premier Paul Painlevé (1917)
  • Premier Georges Clemenceau (1917-1918)
• Supreme Allied Commander
  • Ferdinand Foch (1918)
• Commander-in-chief
  • Joseph Joffre
  • Robert Nivelle
  • Philippe Pétain
• Chief-of-staff
  • Emile Belin
  • Maurice Pelle
  • Edouard de Castelnau
  • Colonel d'Alenson
  • Philippe Pétain
  • Ferdinand Foch
  • Francois Anthoine
  • Edmond Buat

Russia

• Tsar Nicholas II (1914-1917)*
  • Premier Ivan Goremykin (1914-1916)
  • Premier Boris Stürmer (1916)
  • Premier Alexander Trepov (1916-1917)
  • Premier Nikolai Golitsyn (1917)
  • Premier Georgy Lvov (1917)
  • Premier Alexander Kerensky (1917-1918)

Italy

• King Victor Emmanuel III (1915-1918)
  • Prime Minister Antonio Salandra (1915-1916)
  • Prime Minister Paolo Boselli (1916-1917)
  • Prime Minister Vittorio Emanuele Orlando (1917-1918)

United States

• President Woodrow Wilson (1917-1918)
  • plus a Cabinet of seven Secretaries (1917-1918)

Germany

• Kaiser Wilhelm II (1914-1918)*
  • Chancellor Theobald von Bethmann-Hollweg (1914-1917)
  • Chancellor Georg Michaelis (1917)
  • Chancellor Georg von Hertling (1917-1918)
  • Chancellor Max von Baden (1918)

Austria-Hungary

• Emperor Franz Joseph I (1914-1916)†
• Emperor Karl I (1916-1918)
  • Minister-President Karl von Stürgkh (1914-1916)‡
  • Minister-President Ernst von Körber (1916)
  • Minister-President Heinrich Clam-Martinic (1916-1917)
  • Minister-President Ernst Seidler von Feuchtenegg (1917-1918)
  • Minister-President Max Hussarek von Heinlein (1918)
  • Minister-President Heinrich Lammasch (1918)

Turkey

• Sultan Mehmed V (1914-1918)†
• Sultan Mehmed VI (1918)
  • Grand Vizier Said Halim (1914-1917)
  • Grand Vizier Mehmed Talat (1917-1918)
  • Grand Vizier Ahmed Izzet (1918)

Real political control before and during the war was held by the Three Pashas: Mehmed Talat, Ismail Enver, Ahmed Djemal (1914-1918)

Notes

* abdicated

† died

‡ assassinated