The followingoutline is provided as an overview of and topical guide to World War I:

World War I –major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918. It involved all the world'sgreat powers,^[1] which were assembled in two opposing alliances: theAllies (centred on theTriple Entente ofBritain,France andRussia) and theCentral Powers (originally centred on theTriple Alliance ofGermany,Austria-Hungary andItaly).^[2] More than 70 million military personnel, including 60 million Europeans, were mobilised in one of the largest wars in history.^[3][4] More than 9 million combatantswere killed, largely because of great technological advances in firepower without corresponding advances in mobility. It was the sixth deadliest conflict in world history, subsequently paving the way for various political changes such as revolutions in the nations involved.^[5]

World War I can be described as all of the following:

• War
  • Total war
  • World war

World War I was further characterized by the following types of warfare:

• Aerial warfare
• Armoured warfare
• Asymmetric warfare (in some cases)
• Attrition warfare
• Chemical warfare
• Ground warfare
• Modern warfare
• Naval warfare
  • Submarine warfare
    • Antisubmarine warfare
    • Unrestricted submarine warfare
• Trench warfare

Cultural and strategic factors:

• Imperialism
• Militarism
• Nationalism
• Cult of the offensive – Considerations of the advantage of striking first.
  • Preventive war

Destabilizing of theEuropean balance of power:

• Balkanization
• Tensions between Austria and Serbia
  • May Overthrow
  • Pig War
  • Bosnian crisis
• Tensions between Russia and Austria
  • Campaign in andannexation of Bosnia by Austria-Hungary
  • First Balkan War
  • Second Balkan War
• Tensions between France and Germany
  • Franco-Prussian War (1870–1871) – brought the establishment of a powerful and dynamic Germany, causing what was seen as a displacement or unbalancing of power
• Tensions between the United Kingdom and Germany
  • Naval arms race between the United Kingdom and the German Empire
• Tensions between Italy and Austria
  • Annexation of Bosnia by Austria-Hungary

Web of alliances:

• Diplomatic history of World War I
• TheCentral Powers
  • Dual Alliance (Germany and Austria-Hungary)
  • Triple Alliance (1882) (Germany, Austria-Hungary and Italy)
• TheAllies
  • Franco-Russian Alliance (1894)
  • Entente Cordiale between France and the British
  • Anglo-Russian Entente of 1907
  • Triple Entente
• Treaty of London, 1839, about the neutrality ofBelgium
• German Imperial War Council of 8 December 1912

• Assassination of Archduke Franz Ferdinand of Austria
• July Crisis
• British entry into World War I
• French entry into World War I
• German entry into World War I
• Japanese entry into World War I

World War I was fought between theAllies and theCentral Powers.

• German Empire
• Austria-Hungary
• Ottoman Empire
•  Bulgaria

• French Third Republic (includingcolonial forces)
• United Kingdom (includingcolonial forces)
• Russian Empire (untilMarch 1917^[a])
  • Russian Republic (March 1917 -November 1917)
  • Soviet Russia (November 1917 -March 1918)
• Kingdom of Serbia
• Kingdom of Italy^[b] (fromMay 1915) (includingcolonial forces)
• Kingdom of Belgium (includingcolonial forces)
• United States of America (afterApril 1917)

Other states that had military participation:

• Kingdom of Montenegro
• Empire of Japan
• Portuguese Republic (March 1916 and after) (includingPortuguese colonial forces)
• Kingdom of Romania (August 1916 – May 1918, November 1918)
• Kingdom of Greece (November 1916 for theGovernment of National Defence; June 1917 for the whole country)
• Albania
• Brazil (October 1917 and after)
• Armenia (May 1918 and after)
• Czechoslovakia – SeeCzechoslovak Legions
•   Nepal (soldiers served under the British Indian Army)
• Kingdom of Siam
• San Marino (June 1915 and after)
• Sweden (June 1914-early 1916) (1918)

States that declared war, but had no military involvement:

• Andorra
• Bolivia (April 1917 and after)
• China (August 1917 and after)
• Costa Rica (May 1918 and after)
• Cuba (April 1917 and after)
• Ecuador (December 1917 and after)
• Guatemala (April 1918 and after)
• Liberia (August 1917 and after)
• Haiti (July 1918 and after)
• Honduras (July 1918 and after)
• Nicaragua (May 1918 and after)
• Panama (December 1917 and after)
• Peru (October 1917 and after)
• Uruguay (October 1917 and after)

• Allied declarations of war
• British propaganda during World War I
• Convoys in World War I
• German occupation of Luxembourg in World War I
• Roosevelt's World War I volunteers
• Strategic bombing during World War I
  • German strategic bombing during World War I
• World War I conscription in Australia
• World War I naval arms race
• United States Navy operations during World War I
• Military engagements of World War I

• South Arabia during World War I
• Western Front (World War I)
• Eastern Front (World War I)
• West Africa Campaign (World War I)
• East African Campaign (World War I)
• Italian Campaign (World War I)
• Sinai and Palestine Campaign
• Caucasus Campaign
• Mesopotamian Campaign
• Gallipoli Campaign
• Attacks on North America during World War I

• Battle of the Atlantic (1914-1918)
• Adriatic Campaign of World War I
• Naval operations in the Dardanelles Campaign
• Blockade of Germany

• Austria-Hungary during World War I
  • Hungary in World War I
  • Poland during World War I
• Bulgaria during World War I
• Germany during World War I
  • German East Africa during World War I
  • Poland during World War I
• Ottoman Empire during World War I
  • Aliyah and yishuv during World War I
  • Armenia in World War I
    • Western Armenia
    • Armenians in the Ottoman Empire
    • Armenian notables deported from Constantinople in 1915
    • Armenian genocide
      • See alsoArmenian genocide recognition
    • Armenian resistance (1914–1918)
      • Administration for Western Armenia
        • Armenian irregular units
    • Armenian volunteer units
    • Armenian casualties during World War I
  • Seyfo
  • Greek genocide
  • Deportations of Kurds (1916–1934)
  • Prosecution of Ottoman war criminals after World War I

• Serbia during World War I
• France during World War I
  • Summary
  • French foreign policy and the outbreak of the First World War
  • French Army in World War I
  • French villages destroyed in the First World War
• Russia during World War I – food shortages in the major urban centres, and poor morale due to lost battles and heavy losses sustained, brought about civil unrest which led to the February Revolution, the abdication of the Tsar, and the end of the Russian Empire.
  • Russian Revolution (1917) – end of Imperial Russia
    • February Revolution –
      • Russian Provisional Government –
    • October Revolution – beginning of the Soviet Union
  • Poland during World War I
  • Finland during World War I
    • Grand Duchy of Finland
    • Finnish Declaration of Independence
  • Ukraine during World War I
• British Empire during World War I
  • United Kingdom during World War I
  • Australia during World War I
    • Australian women during World War I
  • India in World War I
  • Canada during World War I
  • Newfoundland during World War I
  • New Zealand in World War I
  • South Africa in World War I
    • South African Overseas Expeditionary Force
  • Southern Rhodesia in World War I
  • Hong Kong during World War I
• Italy in World War I
• United States in World War I
  • Puerto Ricans in World War I

• Albania during World War I
• Brazil during World War I
• Czechoslovaks in World War I
  • Czechoslovak Legions
• Greece during World War I
• Japan during World War I
• Montenegro during World War I
• Nepal during World War I
• Portugal during World War I
• Romania during World War I
• Siam during World War I
• San Marino during World War I

• Andorra during World War I
• Bolivia during World War I
• China during World War I
• Costa Rica during World War I
• Cuba during World War I
• Ecuador during World War I
• Guatemala during World War I
• Liberia during World War I
• Haiti during World War I
• Honduras during World War I
• Panama during World War I
• Peru during World War I
• Uruguay during World War I

• Norway in World War I
  • Espionage in Norway during World War I
• Mexico in World War I
• Ireland and World War I
• Montserrat in World War I
• Spain in World War I
• Switzerland during the World Wars - Switzerland did declare a "state of siege".
• Vietnam during World War I
• Afghanistan – received a German diplomatic mission trying to convince it to act against the British in India
• Argentina – Ally to US by treaty (seeABC countries for more information)
• Bhutan
• Chile – Ally to US by treaty (seeABC countries for more information)
• Colombia
• Denmark – Traded with both sides.
• El Salvador
• Ethiopian Empire – received a German diplomatic mission trying to convince it to act against the British in Africa
• Liechtenstein – Had a customs and monetary union with Austria-Hungary.
• Luxembourg – Never declared war on the Central Powers despite being invaded and occupied by Germany.
• Mongolia
• Mexico- Declined an alliance with Germany (seeZimmermann Telegram). An ally to the United States by treaty (seeABC countries).
• Netherlands – An ally of the United Kingdom by treaty. Traded with both sides.
• Norway – Gave naval assistance to the United Kingdom.
• Paraguay
• Persia – Occupied by British and Russian troops.
• Spain – Also treaty bound ally to the United Kingdom.
• Sweden during World War I – Financially supported Germany.
• Venezuela – Supplied the Allies with oil.

• Allied leaders of World War I
• Leaders of the Central Powers of World War I

• List of formations of the United States Army during World War I
  • List of American aero squadrons
• List of Australian divisions in World War I
• List of British armies in World War I
  • List of British corps in World War I
  • List of British divisions in World War I
  • British Land Units of the First World War
  • Royal Flying Corps
• List of Canadian divisions in World War I
• List of French armies in World War I
• List of Indian divisions in World War I
• List of Italian armies in World War I
• Imperial Russian Army formations and units (1914)
  • List of Russian armies in World War I
• Royal Serbian Army

• Austro-Hungarian Armed Forces
  • Austro-Hungarian Army
  • Austro-Hungarian Navy
  • Austro-Hungarian Air Force
• Military of the Ottoman Empire
  • Ottoman Army
  • Ottoman Navy
  • Ottoman Air Force
• Imperial German Army
  • Field armies of Germany in World War I
  • List of Imperial German infantry regiments
  • Luftstreitkräfte
  • Schutztruppe
• Imperial German Navy
  • Seebataillon

• List of military aircraft of Central Powers in WWI
• List of military aircraft of Entente Powers in WWI
• List of aircraft of the Royal Flying Corps
• List of aircraft of the Royal Naval Air Service
• List of military aircraft of Germany

List of infantry weapons of World War I

• British Army uniform and equipment in World War I
• Chemical weapons in World War I
• List of German weapons of World War I
• Romanian military equipment of World War I

• Cross of St. George
• Order of St. George
• Order of Saint Vladimir
• Order of Saint Anna

United States service medals of the World Wars

• American Campaign Medal
• Air Medal
• Asiatic-Pacific Campaign Medal
• Bronze Star
• Distinguished Flying Cross
• European-African-Middle Eastern Campaign Medal
• Medal of Honor
• Silver Star
• World War I Victory Medal

• Air Force Cross, from June 1918
• Distinguished Flying Cross
• Military Cross
• Military Medal
• Order of the Bath
• Order of the British Empire
• Victoria Cross
• 1914 Star

• Commemorative war medal
• Croix de Guerre
• Dardanelles campaign medal
• Orient campaign medal

• House Order of Hohenzollern
• Iron Cross
• Order of the Red Eagle
• Pour le Mérite also known as the "Blue Max"

• Order of Karađorđe's Star

• Military Order of Maria Theresa
• Military Merit Cross

The First World War saw many instances ofwar crimes being committed by both the Allied and Central powers:

• Armenian genocide
• Greek genocide

• Massacres of Albanians in World War I
• Rape of Belgium
• Siege of Tsingtao
• Štip massacre
• Surafend massacre
• Surdulica massacre

• List of German-sponsored acts of terrorism during World War I

• Raid on Scarborough, Hartlepool and Whitby
• Turnip Winter

• Armistice of Salonica (September 29, 1918) - surrender of Bulgaria
• Armistice of Mudros (October 30, 1918) – surrender of the Ottoman Empire
• Armistice of Villa Giusti (November 3, 1918) – surrender of Austria-Hungary
• Armistice with Germany (November 11, 1918) – surrender of Germany

• World War I reparations
• Dissolution of the Austro-Hungarian Empire into several successor states:
  • Czechoslovakia
  • Yugoslavia
  • First Republic of Austria
  • Hungarian Democratic Republic
  • Second Polish Republic
• Cession byAustria-Hungary ofTransylvania andBukovina toRomania.
• Cession byAustria-Hungary of the southern half of theCounty of Tyrol andTrieste toItaly
• Establishment of theFirst Republic of Armenia
• FurtherBalkanization
• World War II
  • World War I was one of the main causes of World War II

• List of books about World War I
• List of World War I films
• World War I in literature
• World War I in popular culture

• Germany's Aims in the First World War

• Fiction based on World War I

• World War I reenactment
• WWI memorials
  • World War I Memorial (Berwick, Pennsylvania)
  • World War I Memorial (Atlantic City, New Jersey)
  • World War I Memorial (East Providence, Rhode Island)
• WWI veterans

• Timeline of World War I
• Opposition to World War I
• Outline of war
• Outline of World War II

• Bade, Klaus J.; Brown, Allison (tr.) (2003).Migration in European History. The making of Europe. Oxford: Blackwell.ISBN 978-0-631-18939-8.OCLC 52695573. (translated from the German)
• Keegan, John (1998).The First World War. Hutchinson.ISBN 978-0-09-180178-6.
• Willmott, H.P. (2003).World War I. Dorling Kindersley.ISBN 978-0-7894-9627-0.OCLC 52541937.

• Bond, Brian. "The First World War" in C. L. Mowat, ed.The New Cambridge Modern History: Vol. XII: The Shifting Balance of World Forces 1898-1945 (2nd ed. 1968)online pp 171–208.

• The War to End All Wars on BBC
• WWI Service Questionnaires at Gettysburg College
• A multimedia history of World War I
• The Heritage of the Great War, Netherlands
• Collection of World War I Color Photographs
• The Commonwealth War Graves Commission
• Royal Engineers Museum Royal Engineers and the First World War
• World War I : Soldiers Remembered Presented by the Washington State Library and Washington State Archives
• The World War I Document Archive Wiki

• World War I
• Outlines of wars
• Outlines

• Articles with short description
• Short description matches Wikidata
• Pages using Sister project links with default search