# Timeline of World War I

This is a list of the events of World War I in chronological order.

## 1914

| Dates | Theater/Front/Campaign | Events |
| June 28 | Politics | Assassination of Archduke Franz Ferdinand, heir to the Austro-Hungarian throne, who was killed in Sarajevo along with his wife Sophie, Duchess of Hohenberg by Gavrilo Princip, a Bosnian Serb. |
| July 5 | Politics | Austria-Hungary seeks German support for a war against Serbia in case of Russian military intervention. German Empire gives assurances of support. |
| July 23 | Politics | Beginning of the "Black Week". Austria-Hungary sends an ultimatum to Kingdom of Serbia. Kingdom of Serbia responds that night, agreeing to most but not all terms of the ultimatum. The Serbian response is seen as satisfactory by the Kaiser, but German diplomats do not pressure Austria to make peace. (Details) |
| July 24 | Balkan | Kingdom of Serbia mobilizes, expecting Austria to declare war after the refusal of the ultimatum. |
| July 25 | Eastern | Austria mobilizes against Serbia. Russia enters the period preparatory to war (partial mobilization). |
| July 28 | Politics | To my peoples. Austria-Hungary declares war on Serbia. |
| July 29 | Politics | Willy–Nicky correspondence. Wilhelm II, German Emperor and Nicholas II of Russia communicate via telegram. |
| July 30 | Politics | Germany sends Russia an ultimatum. |
| July 31 | Politics | Sweden announces neutrality in the conflict between Austria-Hungary and Serbia |
| July 31 | Politics | Russia mobilizes for war. |
| August 1 | Politics | Germany declares war on Russia and mobilizes. |
| August 1 | Western | France mobilizes. |
| August 1 | Politics | Italy declares its neutrality. |
| August 1 | Politics | German–Ottoman alliance. German Empire and the Ottoman Empire sign a secret alliance treaty. |
| August 2 | Western | Germany invades Luxembourg. (Details) |
| August 2 | Western | Skirmish at Joncherey, first military action on the Western Front. |
| August 2 – 26 | Western | Germany besieges and captures fortified Longwy, "the Iron Gate to Paris", near the Luxembourg border, opening France to mass German invasion. |
| August 3 | Politics | Germany declares war on France. Belgium denies permission for German forces to pass through to the French border. |
| August 3 | Politics | Switzerland declares its neutrality and mobilises for defence purposes. |
| August 3 | Politics | Sweden declares neutrality in the conflict between Germany, Russia and France |
| August 4 | Western | German invasion of Belgium (1914) to outflank the French army. Rape of Belgium |
| August 4 | Politics | Britain protests against the violation of Belgian neutrality, guaranteed by the Treaty of London (1839), The German Chancellor replies that the treaty is just a chiffon de papier (a scrap of paper). The United Kingdom declares war on Germany, automatically including all dominions, colonies, etc. of the British Empire including Canada, Australia, and British India. (Details) |
| August 4 | Politics | The United States declares neutrality. |
| August 5 – 16 | Western | Battle of Liège. The Germans besiege and then capture the fortresses of Liège, Belgium. |
| August 5 | Asian and Pacific | First weapon fired in Melbourne, Australia, by Australian troops |
| August 5 | Asian and Pacific | German Steamer SS Pfalz surrenders after being fired on by Fort Nepean, south of Melbourne, Australia (Details) |
| August 5 | Politics | Montenegro declares war on Austria-Hungary. |
| August 5 | Middle Eastern | The Ottoman Empire closes the Dardanelles. |
| August 6 | Politics | Austria-Hungary declares war on Russia. |
| August 6 | Politics | Kingdom of Serbia declares war on Germany. |
| August 7 |
| August 7 | Politics | Spain declares "the strictest neutrality." (Details) |
| August 7 – September 6 | Western | Battle of the Frontiers. The Germans obtain a victory against the British Expeditionary Force and France's Fifth Army. |
| August 7 – 10 | Western | Battle of Mulhouse, a phase of the Battle of the Frontiers. |
| August 8 | Politics | Montenegro declares war on Germany. |
| August 8 | Politics | Sweden and Norway declare neutrality in the general conflict |
| August 9 | African, Togoland | The Togoland Campaign begins. |
| August 11 | Politics | France declares war on Austria-Hungary. |
| August 12 | Politics | The United Kingdom declares war on Austria-Hungary. |
| August 12 | Western | Battle of Halen, a phase of the Battle of the Frontiers. |
| August 14 – 25 | Western | Battle of Lorraine, a phase of the Battle of the Frontiers. |
| August 14 – 24 | Western | Battle of Dinant, during the German invasion of Belgium. Including Sack of Dinant (August 23) |
| August 15 | African, East African | German troops cross into East Africa Protectorate and occupy Taveta. (Details) |
| August 15 – 24 | Balkan, Serbian | The Serbs defeat the Austro-Hungarians at the Battle of Cer. |
| August 17 | Eastern | Battle of Stallupönen. The Russian army enters East Prussia. |
| August 20 | Eastern | The Germans attack the Russians in East Prussia at the Battle of Gumbinnen. The attack is a failure in addition to being a deviation from the Schlieffen Plan. |
| August 20 | Western | The Germans occupy Brussels. |
| August 20 | Western | Battle of Morhange-Sarrebourg, a phase of the Battle of Lorraine. |
| August 21 – 23 | Western | Battle of Charleroi, a phase of the Battle of the Frontiers. |
| August 21 – 23 | Western | Battle of the Ardennes, a phase of the Battle of the Frontiers. |
| August 23 | Politics | Japan declares war on Germany. (Details) |
| August 23 | Western | Battle of Mons, a phase of the Battle of the Frontiers. |
| August 23 – 30 | Eastern | Battle of Tannenberg: the Russian army undergoes a heavy defeat by the Germans. |
| August 23 – September 11 | Eastern | Battle of Galicia. The Russians capture Lviv. |
| August 23 – 25 | Eastern | Battle of Kraśnik, a phase of the Battle of Lemberg. The Austro-Hungarian First Army defeats the Russian Fourth Army. |
| August 24 – 26 | Western | Action of Elouges |
| August 24 – 26 | Western | Battle of the Trouée de Charmes, a phase of the Battle of Lorraine. |
| August 24 – September 7 | Western | Siege of Maubeuge. The Germans besiege and capture the Maubeuge Fortress. |
| August 24 – September 5 | Western | The Allied Great Retreat to the River Marne. |
| August 25 | Politics | Japan declares war on Austria-Hungary. |
| August 25 | African, Kamerun | Battle of Tepe: The Kamerun campaign begins. |
| August 26 | African, Togoland | British and French forces conquer Togoland, a German protectorate in West Africa. (Details) |
| August 26 | Western | Rearguard Affair of Le Grand Fayt |
| August 26 | Western | Battle of Le Cateau results in an Allied retreat. |
| August 26 – 30 | Eastern | Battle of Gnila Lipa, a phase of the Battle of Lemberg. |
| August 26 – September 2 | Eastern | Battle of Komarów (1914), part of the Battle of Lemberg. |
| August 26, 1914 – February 18, 1916 | African, Kamerun | Siege of Mora |
| August 27 | Western | Rearguard Affair of Étreux |
| August 27 – November 7 | Asian and Pacific | Siege of Tsingtao: British and Japanese forces capture the German-controlled port of Qingdao in Republic of China (1912–1949). |
| August 28 | Naval | The Royal Navy wins the First Battle of Heligoland Bight (1914) in the North Sea. |
| August 28 | Politics | Austria-Hungary declares war on Belgium. |
| August 29 – 30 | Western | Battle of St. Quentin (1914), also known as Battle of Guise. Orderly Allied retreat. |
| August 29 – 31 | African, Kamerun | First Battle of Garua |
| August 29 – 30 | Asian and Pacific | Occupation of German Samoa. New Zealand occupies German Samoa (later Samoa). |
| September 1 | Western | Affair of Néry |
| September 1 | Politics | Saint Petersburg renamed Petrograd, removing German words "Burg" and "Sankt". |
| September 3 – 11 | Eastern | Austro-Hungarian defeat at the Battle of Rawa, a phase of the Battle of Lemberg. |
| September 5 | Naval, Atlantic | British scout cruiser HMS Pathfinder (1904) is sunk by U-boat SM U-21 off Scotland. |
| September 5–12 | Western | First Battle of the Marne. The German advance on Paris is halted, marking the failure of the Schlieffen Plan. |
| September 5–12 | Western | Battle of the Ourcq, a phase of the First Battle of the Marne. |
| September 5–12 | Western | Battle of the Two Morins |
| September 6 | African, Kamerun | Battle of Nsanakong |
| September 6–12 | Western | Battle of the Marshes of Saint-Gond, a phase of the First Battle of the Marne. |
| September 6–12 | Western | Battle of Vitry, a phase of the First Battle of the Marne. |
| September 6–12 | Western | Battle of Revigny, a phase of the First Battle of the Marne. |
| September 7 – September 24 | Balkan, Serbian | Battle of the Drina |
| September 7 | Asian and Pacific | Fanning Raid |
| September 7–14 | Eastern | First Battle of the Masurian Lakes: The Russian Army of the Neman withdraws from East Prussia with heavy casualties. |
| September 9 | Politics | Theobald von Bethmann Hollweg lays out Germany's war aims. (Details) |
| September 11 | Asian and Pacific | Battle of Bita Paka |
| September 13 | African, South West Africa | South West Africa campaign. Troops from South Africa begin invading German South West Africa. |
| September 13–28 | Western | The First Battle of the Aisne ends in a substantial draw. The Race to the Sea begins. |
| September 14 | Politics | Erich von Falkenhayn replaces Helmuth von Moltke the Younger as German Chief of Staff. |
| September 14–17 | Asian and Pacific | Siege of Toma. Most German forces in German New Guinea surrender to the Australians then or over the following year. |
| September 15, 1914 - Feb 4, 1915 | African, South West Africa | Maritz rebellion. Boers leader Manie Maritz revolts in South Africa. |
| September 19 – October 11 | Western | Battle of Flirey |
| September 20 | Naval, African, East African | Battle of Zanzibar, German naval victory. |
| September 22 | Asian and Pacific | Bombardment of Papeete |
| September 22 | Asian and Pacific | Bombardment of Madras. German light cruiser SMS Emden attacks Chennai. |
| September 22–26 | Western | First Battle of Picardy |
| September 24 | Eastern | The Siege of Przemyśl begins. |
| September 26 | African, South West Africa | Battle of Sandfontein |
| September 25–29 | Western | First Battle of Albert (1914) |
| September 28 – October 10 | Western | Siege of Antwerp (1914). The Germans besiege and capture Antwerp, Belgium. |
| September 29–30 | Asian and Pacific | Japan occupies the Marshall Islands. |
| September 29 – October 31 | Eastern | Battle of the Vistula River, also known as Battle of Warsaw. |
| October 1914 – July 11, 1915 | Naval, African, East African | Battle of Rufiji Delta, German cruiser SMS Königsberg (1905) destroyed. |
| October 1–4 | Western | First Battle of Arras (1914) |
| October 9 – November 1 | Balkan, Serbian | Central powers control Belgrade. (Details) |
| October 10 – November 2 | Western | Battle of La Bassée |
| October 12 – November 2 | Western | First Battle of Messines (1914) |
| October 13 – November 2 | Western | Battle of Armentières |
| October 16–31 | Western | Battle of the Yser. French and Belgian forces secure the coastline of Belgium. |
| October 19 – November 22 | Western | The First Battle of Ypres ends the Race to the Sea. The Germans are prevented from reaching Calais and Dunkirk. |
| October 18, 1914 – July 9, 1915 | African, South West Africa | German campaign in Angola. Clashes between German and Portuguese forces in the Portuguese Angola-German South West Africa border, without declaration of war. |
| October 28 | Naval, Asian and Pacific | Battle of Penang. The German cruiser Emden sinks two British warships in the Strait of Malacca. |
| October 29 | Naval, Eastern | Black Sea raid. Ottoman warships bombard the Russian ports of Odessa and Sevastopol. |
| November 1 | Politics | Russia declares war on the Ottoman Empire. |
| November 1 | Naval | Battle of Coronel. Von Spee's German cruiser squadron defeats a Royal Navy squadron under Christopher Cradock off Chile. |
| November 2 | Naval, Atlantic | The United Kingdom begins the naval blockade of Germany. (Details) |
| November 2 | Politics | Serbia declares war on the Ottoman Empire. |
| November 2–21 | Middle Eastern, Caucasian | Bergmann Offensive, first military engagement in the Caucasus of the First World War. |
| November 3 | Politics | Montenegro declares war on the Ottoman Empire. |
| November 3 | African, East African | Battle of Kilimanjaro |
| November 3–5 | African, East African | Von Lettow-Vorbeck's German colonial forces defeat the British at the Battle of Tanga, German East Africa. |
| November 5 | Politics | France and the United Kingdom declare war on the Ottoman Empire. |
| November 6–8 | Middle Eastern, Mesopotamian | Fao Landing, British and Indians besiege the fortress at Fao. |
| November 7 | Asian and Pacific | Japanese Forces capture the Naval Base at Tsingtao. (Details) |
| November 11 | Politics | Sultan Mehmed V declares Jihad on the Allies of World War I. |
| November 11–22 | Middle Eastern, Mesopotamian | Battle of Basra (1914) |
| November 11 – December 6 | Eastern | Battle of Łódź (1914) (also known as Silesian offensive). |
| November 13 | African, East African | Battle of El Herri: Worst French defeat in Morocco at the hands of the Zayanes. |
| November 16 – December 15 | Balkan, Serbian | Battle of Kolubara, Austro-Hungarians withdraw from Serbia. |
| November 19 | Politics | Bolshevik representatives at the State Duma arrested and exiled to Siberia. |
| November 23 | Middle Eastern, Mesopotamian | Basra is occupied by the British. |
| December 1 – 13 | Eastern | Battle of Limanowa |
| December 3 – 9 | Middle Eastern, Mesopotamian | Battle of Qurna |
| December 8 | Naval | Battle of the Falkland Islands. Von Spee's German cruiser squadron is defeated by the Royal Navy. |
| December 10 | Western | Hill 60 (Ypres) captured by the Germans. |
| December 14 | Middle Eastern, Persian | Persian campaign (World War I). Ottomans occupy the Persian border town of Qatur as a bridgehead to the Caucasus, but withdraw after their defeat at Sarıkamış. |
| December 16 | Naval, Atlantic | Raid on Scarborough, Hartlepool and Whitby. The German fleet shells Scarborough, North Yorkshire, Hartlepool, and Whitby England. |
| December 18–19 | Politics | Christian X, Gustaf V, and Haakon VII meet at Malmö to discuss neutrality, which leads to Denmark joining Sweden and Norway in neutrality |
| December 18 – 22 | Western | Battle of Givenchy |
| December 17, 1914 – January 13, 1915 | Western | First Battle of Artois |
| December 20 | Western | Fighting begins at Perthes, Ardennes. |
| December 20, 1914 – 17 March 1915 | Western | First Battle of Champagne |
| December 22 | Western | Fighting begins at Noyon. |
| December 22, 1914 – January 17, 1915 | Middle Eastern, Caucasian | The Russians win the Battle of Sarikamish, Caucasia. |
| December 24 – 26 | Western | In some sectors of the Western Front, an unofficial Christmas truce is observed between German and British forces. |
| December 25 – January 18, 1915 | Middle Eastern, Caucasian | Battle of Ardahan |

## 1915

| Dates | Theater/Front/Campaign | Events |
| January 2 | Eastern | The Russian offensive in the Carpathians begins. It will continue until April 12. |
| January 4–11 | Middle Eastern, Persian | Ottomans occupy Urmia and Tabriz by surprise. |
| January 18 | Politics | Japan attempts to impose its Twenty-One Demands on neutral China. |
| January 18–19 | African, East African | Battle of Jassin. |
| January 19 – December 22 | Western | Battle of Hartmannswillerkopf, series of battles fought to control the peak. |
| January 24 | Naval | Battle of Dogger Bank between squadrons of the British Grand Fleet and the German Hochseeflotte. |
| January 24–26 | African, East African | Chilembwe uprising led by John Chilembwe in Nyasaland. |
| January 28 – February 3 | Middle Eastern, Sinai and Palestine | The Ottomans fail to capture the Suez Canal in the First Suez Offensive. |
| January 30 | Middle Eastern, Persian | The Russians take Tabriz. |
| January 31 | Eastern | Battle of Bolimov. First German use of chemical weapons. |
| February 4 | Naval, Atlantic | Germany begins unrestricted submarine warfare against merchant vessels. |
| February 4 | African, South West Africa | Jan Kemp surrenders. End of the Maritz Rebellion. |
| February 4 | African, South West Africa | Battle of Kakamas: German invasion of South Africa repelled. |
| February 7–22 | Eastern | Second Battle of the Masurian Lakes. The Russian X Army is defeated. |
| February 15 | Asian and Pacific | Troops in Singapore mutiny against the British |
| February 19 | Middle Eastern, Gallipoli | British and French naval attack on the Dardanelles. The Gallipoli Campaign begins. |
| March 5 | Politics | Great Britain and France promise Russia Constantinople. |
| March 7 | Middle Eastern, Persian | Ottomans retreat to Qotur, pushed by a Russian counteroffensive. |
| March 10 – March 13 | Western | Battle of Neuve Chapelle. After an initial success, a British offensive is halted. |
| March 14 | Naval | Battle of Más a Tierra. The last remnant of the German East Asia Squadron is sunk and its crew interned in neutral Chile. |
| March 18 | Naval, Middle Eastern, Gallipoli | Battle of 18 March. The British and French unsuccessfully try to force the Dardanelles, losing 3 Pre-Dreadnought Battleships |
| March 22 | Eastern | The Siege of Przemyśl ends. The Russians capture the fortress. |
| April 5 – May 5 | Western | First Battle of Woevre. |
| April 12–14 | Middle Eastern, Mesopotamian | Battle of Shaiba. |
| April 15 | Middle Eastern, Persian | Battle of Dilman |
| April 19 – May 17 | Middle Eastern, Caucasian | The Ottomans besiege the Armenian city of Van. |
| April 22 – May 25 | Western | The Second Battle of Ypres, which ends in a stalemate. Germany first uses poison gas. |
| April 22–23 | Western | Battle of Gravenstafel, First stage of the Second Battle of Ypres. |
| April 24 | Politics | Deportation of Armenian intellectuals to Ankara, first act of the Armenian genocide. |
| April 24 – May 5 | Western | Battle of St Julien, part of the Second Battle of Ypres. |
| April 25 | Middle Eastern, Gallipoli | Allied forces land on Gallipoli, landing at Ari Burnu, soon renamed Anzac Cove, and Cape Helles. (Details) |
| April 26 | Politics | Treaty of London between the Entente and Italy. |
| April 26 | African, South West Africa | Battle of Trekkopjes. |
| April 28 | Middle Eastern, Gallipoli | First Battle of Krithia. The Allied advance is repelled. |
| April 29 | African, Kamerun | Battle of Gurin. |
| May 1 | Eastern | The Gorlice-Tarnów Offensive begins: the German troops under General Mackensen break through the Russian lines in Galicia. |
| May 1 | Middle Eastern, Gallipoli | Battle of Eski Hissarlik. |
| May 3 | Middle Eastern, Gallipoli | Troops withdraw from Anzac Cove. |
| May 3 | Politics | Italy revokes its commitment to a defensive alliance with Germany and Austria-Hungary. |
| May 6–8 | Middle Eastern, Gallipoli | Second Battle of Krithia. The Allied attempts at advancing are thwarted again. |
| May 7 | Naval, Atlantic | The British liner Lusitania is sunk by a German U-boat. |
| May 8–13 | Western | Battle of Frezenberg Ridge, Part of the Second Battle of Ypres. |
| May 9 | Western | Beginning of the Second Battle of Artois, with the Battle of Aubers |
| May 10 | Eastern | Troops from Hungary rout the Russians at Jarosław. Lviv is again in Austrian hands. |
| May 11 | Middle Eastern, Gallipoli | Armistice called at Gallipoli to bury the dead. (Details) |
| May 12 | African, South West Africa | Windhoek, capital of German South-West Africa, is occupied by South African troops. |
| May 15–25 | Western | Battle of Festubert. |
| May 16 – June 23 | Eastern | Battle of Konary. |
| May 23 | Politics | Italy declares war on Austria-Hungary. (Details) |
| May 24–25 | Western | Battle of Bellewaarde, final phase of the Second Battle of Ypres. |
| May 31 – June 10 | African, Kamerun | Second Battle of Garua. |
| June–September | Eastern | The Russian Great Retreat from Poland and Galicia. |
| June 4 | Middle Eastern, Gallipoli | Third Battle of Krithia. Yet another Allied failure. |
| June 4 | Eastern | The Russians leave Przemyśl. (Details) |
| June 21–23 | African, East African | Battle of Bukoba. |
| June 22 | Eastern | Mackensen again breaks through the Russian lines in the Lviv area. (Details) |
| June 23 – July 7 | Italian | First Battle of the Isonzo. |
| June 27 | Eastern | The Austro-Hungarians re-enter Lviv. (Details) |
| June 28 – July 5 | Middle Eastern, Gallipoli | The British win the Battle of Gully Ravine. |
| June 29 | African, Kamerun | Battle of Ngaundere |
| July 1 | Air | First aerial victory by a synchronized gun-armed fighter aircraft (Details) |
| July 1 | African, South West Africa | Battle of Otavi. |
| July 9 | African, South West Africa | The German forces in South-West Africa surrender. |
| July 10–26 | Middle Eastern, Caucasian | Battle of Manzikert. |
| July 18 – August 3 | Italian | Second Battle of the Isonzo. |
| July 25 | Italian | Italians capture Cappuccio Wood. (Details) |
| July 25 | Air | First Victoria Cross awarded to a British combat pilot (Details) |
| July 27–31 | Middle Eastern, Caucasian | Battle of Kara Killisse. |
| August 5 | Eastern | The Germans occupy Warsaw. (Details) |
| August 6–10 | Middle Eastern, Gallipoli | Battle of Lone Pine, part of the August Offensive. |
| August 6–13 | Middle Eastern, Gallipoli | Battle of Krithia Vineyard, part of the August Offensive. |
| August 6–15 | Middle Eastern, Gallipoli | Allies land at Suvla Bay, a phase of the August Offensive. |
| August 6–21 | Middle Eastern, Gallipoli | Battle of Sari Bair, part of the August Offensive. Last and unsuccessful attempt by the British to seize the Gallipoli peninsula. |
| August 7 | Middle Eastern, Gallipoli | Battle of the Nek, a phase of the August Offensive. |
| August 7–19 | Middle Eastern, Gallipoli | Battle of Chunuk Bair, a phase of the August Offensive. |
| August 19 | Naval, Atlantic | A German U-boat sinks the liner SS Arabic (1902). 44 died including 3 Americans |
| August 21 | Middle Eastern, Gallipoli | Scimitar Hill, a phase of the August Offensive. |
| August 21 | Politics | Italy declares war on the Ottoman Empire. |
| August 21–29 | Middle Eastern, Gallipoli | Battle of Hill 60, part of the August Offensive. |
| August 26 – September 19 | Eastern | Sventiany Offensive, a phase of the Gorlice-Tarnow Offensive. |
| September 1 | Naval, Atlantic | Germany suspends unrestricted submarine warfare. (Details) |
| September 5–8 | Politics | The Zimmerwald Conference of anti-militarist European socialist parties is held in Zimmerwald, Switzerland. |
| September 5 | Eastern | Nicholas II removes Grand Duke Nicholas Nikolayevich as Commander-in-Chief of the Russian Army, personally taking that position. |
| September 15 – November 4 | Western | Third Battle of Artois. |
| September 19 | Eastern | The Germans occupy Vilnius. The Gorlice-Tarnów Offensive ends. |
| September 25–28 | Western | Battle of Loos, a major British offensive, fails. |
| September 25 – October 15 | Western | Battle of the Hohenzollern Redoubt, a phase of the Battle of Loos. |
| September 25 – November 6 | Western | Second Battle of Champagne. |
| September 28 | Middle Eastern, Mesopotamian | Battle of Es Sinn. |
| October 3 | Balkan, Macedonian | Allies land troops at Salonika in Greece to aid Serbia. |
| October 7 – December 4 | Balkan, Serbian | Serbia is invaded by Germany, Austria-Hungary, and Bulgaria. |
| October 12 | Politics | Edith Cavell executed. |
| October 14 | Politics | Bulgaria declares war on Serbia (Details) |
| October 14 – November 9 | Balkan, Serbian | Morava Offensive, a phase of the Central Powers Invasion of Serbia, Bulgarians break through Serbian lines. |
| October 14 – November 15 | Balkan, Serbian | Ovche Pole Offensive, a phase of the Central Powers invasion of Serbia, Bulgarians break through Serbian lines. |
| October 15 | Politics | The United Kingdom declares war on Bulgaria. |
| Politics | Montenegro declares war on Bulgaria. |
| October 16 | Politics | France declares war on Bulgaria. |
| October 17 – November 21 | Balkan, Macedonian | Battle of Krivolak, first of the Salonika front. |
| October 18 – November 4 | Italian | Third Battle of the Isonzo |
| October 19 | Politics | Italy and Russia declare war on Bulgaria. |
| October 27 | Politics | Andrew Fisher resigns as Prime Minister of Australia; he is replaced by Billy Hughes. |
| October 29 | Politics | René Viviani resigns as Prime Minister of France; he is replaced by Aristide Briand. |
| November 4–6 | African, Kamerun | Battle of Banjo. |
| November 10 | Middle Eastern, Persian | Pro-Central Powers Iranians seize Shiraz from pro-Entente forces and arrest all British citizens in the city. |
| November 10 – December 2 | Italian | Fourth Battle of the Isonzo |
| November 10 – December 4 | Balkan, Serbian | Kosovo Offensive, a phase of the Central Powers invasion of Serbia, Serbians pushed into Albania. |
| November 14–30 | Middle Eastern, Persian | Russian forces from the Caucasus occupy Tehran. |
| November 17 | African, North African | Armed by Ottomans and Germans, the Libyan Senussi cross the border and attack Egypt from the west. (Details) |
| November 22–25 | Middle Eastern, Mesopotamian | Battle of Ctesiphon, in present-day Iraq. |
| November 27 | Balkan, Serbian | The Serbian army collapses. It will retreat to the Adriatic Sea and be evacuated by the Italian and French Navies. (Details) |
| December – July, 1916 | Naval, African, East African | Battle of Lake Tanganyika. |
| December 6–12 | Balkan, Macedonian | Battle of Kosturino |
| December 7 | Middle Eastern, Mesopotamian | The First Siege of Kut, Mesopotamia, by the Ottomans begins. |
| December 15 | Middle Eastern, Persian | Russians occupy Hamadan. |
| December 18 | Middle Eastern, Gallipoli | Gallipoli evacuations, a major Ottoman victory and a "disaster for the Allies." |
| December 19 | Western | Douglas Haig replaces John French as commander of the British Expeditionary Force. |
| December 23 | African, Kamerun | Carl Zimmermann orders the retreat of all German forces and civilians in Kamerun to the Spanish colony of Río Muni. |

## 1916

| Dates | Theater/Front/Campaign | Events |
| January 5–17 | Balkan | Austro-Hungarian offensive against Montenegro, which capitulates. (Details) |
| January 6–7 | Balkan | Battle of Mojkovac |
| January 6–8 | Middle Eastern | Battle of Sheikh Sa'ad, a phase of the First Siege of Kut. |
| January 9 | Gallipoli | The Gallipoli Campaign ends in an Allied defeat and an Ottoman victory. (Details) |
| January 10 – February 16 | Caucasian | Battle of Erzurum. |
| January 11 | Balkan | Corfu occupied by the Allies. (Details) |
| January 13 | Middle Eastern | Battle of Wadi, a phase of the First Siege of Kut. (Details) |
| January 21 | Middle Eastern | Battle of Hanna, a phase of the First Siege of Kut. |
| January 24 | Naval | Reinhard Scheer is appointed commander of Germany's Hochseeflotte. (Details) |
| January 27 | Politics | Conscription introduced in the United Kingdom by the Military Service Act 1916. (Details) |
| February 5 – April 15 | Caucasian | Trebizond Campaign. |
| February 12 | African | Battle of Salaita Hill. |
| February 21 | Western | The Battle of Verdun begins. |
| February 26 | African | Battle of Agagia: Senussi rebellion suppressed by the British. |
| February 28 | African | German Kamerun (Cameroon) surrenders. (Details) |
| March 1 | Naval | Germany resumes unrestricted submarine warfare. (Details) |
| March 1–15 | Italian | Fifth Battle of the Isonzo. |
| March 2 – August 4 | Caucasian | Battle of Bitlis. |
| March 8 | Middle Eastern | Battle of Dujaila: a British attempt to relieve Kut failed. (Details) |
| March 9 | Politics | Germany declares war on Portugal. Portugal officially enters the war. (Details) |
| March 11–12 | African | Battle of Latema Nek. |
| March 14 | Politics | The Manifesto of the Sixteen, declaring Kropotkinist-anarchist support of the Allied war effort, is published. (Details) |
| March 15 | Politics | Austria-Hungary declares war on Portugal. |
| March 16 – November 6 | African | British preemptively invade the Sultanate of Darfur and annex it to the Anglo-Egyptian Sudan. (Details) |
| March 18 | African | Battle of Kahe. |
| March 18 – April | Eastern | Lake Naroch Offensive. |
| April 24–29 | Politics | Easter Rising by Irish rebels for independence from the United Kingdom. (Details) |
| April 24–30 | Politics | The Kienthal Conference, the second meeting of the anti-war socialist Zimmerwald Movement, is held in Kienthal, Switzerland. (Details) |
| April 27–29 | Western | Gas attacks at Hulluch. |
| April 29 | Middle Eastern | The British forces under siege at Kut surrender to the Ottomans, first siege of Kut ends. (Details) |
| May 7–10 | African | Battle of Kondoa Irangi. |
| May 10 | Naval | Germany suspends unrestricted submarine warfare. (Details) |
| May 15 – June 10 | Italian | Austro-Hungarian Strafexpedition in Trentino. (Details) |
| May 16 | Politics | Signing of the Sykes-Picot Agreement between Britain and France defining their proposed spheres in the Middle East. (Details) |
| May 18 | Middle Eastern | Russian forces in Persia link up with the British in Mesopotamia, but it is too late. (Details) |
| May 31 – June 1 | Naval | Battle of Jutland between Britain's Grand Fleet and Germany's Hochseeflotte. (Details) |
| June 2–14 | Western | Battle of Mont Sorrel. |
| June 3 | Middle Eastern | Russians fail to encircle Ottoman forces in Persia. (Details) |
| June 4 | Eastern | The Brusilov Offensive begins. |
| June 5 | Middle Eastern | The Arab Revolt in Hejaz begins. (Details) |
| June 5 | Naval | HMS Hampshire is sunk off the Orkney Islands; Lord Kitchener dies. (Details) |
| June 8 | Naval | In the Adriatic Sea the Italian troopship SS Principe Umberto is sunk by an Austro-Hungarian submarine. It is the deadliest sinking of the war, with 1,900 lives lost. |
| June 10 | Politics | Italy: Paolo Boselli succeeds Antonio Salandra as Prime Minister. (Details) |
| June 10 | Middle Eastern | The Siege of Medina begins. |
| June 10 – July 4 | Middle Eastern | Battle of Mecca, Arabs capture the city. (Details) |
| June 12 | Middle Eastern | Percy Sykes marches on Kerman to link up with the Russian forces in central-northern Persia. |
| June 30 | Western | Battle of the Boar's Head, diversion from the Battle of the Somme which began the next day. |
| July | Middle Eastern | Battle of Taif. (Details) |
| July 1 | Western | The Battle of the Somme begins. (Details) |
| July 1–3 | Politics | The Social Democratic Party wins a majority in the parliament of the Russian-ruled Grand Duchy of Finland. (Details) |
| July 1–13 | Western | Second Battle of Albert (Opening phase of the Battle of the Somme). (Details) |
| July 1–2 | Western | British capture Fricourt during the Second Battle of Albert. (Details) |
| July 2 | Middle Eastern | Ottoman counter-attack into Persia reaches Kermanshah. (Details) |
| July 2–25 | Caucasian | Battle of Erzincan. |
| July 3–7 | Western | British capture La Boisselle during the Second Battle of Albert. (Details) |
| July 3–12 | Western | British capture Mametz Wood during the Second Battle of Albert. (Details) |
| July 3–17 | Western | British capture Ovillers during the Second Battle of Albert and Battle of Bazentin Ridge. (Details) |
| July 4–6 | Eastern | Battle of Kostiuchnowka. |
| July 7–11 | Western | British capture Contalmaison during the Second Battle of Albert. (Details) |
| July 8–14 | Western | British capture Trônes Wood during the Second Battle of Albert. (Details) |
| July 14–17 | Western | Battle of Bazentin Ridge (Initial phase of the Battle of the Somme) (Details) |
| July 14 – September 15 | Western | Battles for Longueval and Delville Wood (Initial phase of the Battle of the Somme) (Details) |
| July 19–20 | Western | Battle of Fromelles (Initial phase of the Battle of the Somme). |
| July 23 – August 7 | Western | Battle of Pozières (Initial phase of the Battle of the Somme) (Details) |
| July 24 – August 8 | Eastern | Battle of Kowel. |
| July 30 | | German agents sabotage munition factories in Jersey City that supply the Allies, causing the Black Tom explosion. |
| August 3–5 | Middle Eastern | Battle of Romani. Ottoman attack on the British in the Sinai peninsula fails. (Details) |
| August 6–17 | Italian | Sixth Battle of the Isonzo. The Italians capture Gorizia (August 9). (Details) |
| August 6 | Italian | Battle of Doberdo, part of the Sixth Battle of Isonzo. |
| August 9–18 | Balkan | First battle of Doiran. (Details) |
| August 10 | Middle Eastern | Ottomans take Hamadan. (Details) |
| August 24 | African | Battle of Mlali. |
| August 27 | Balkan | Romania enters the war on the Entente's side. Her army is defeated in a few weeks. |
| August 27 – December | Balkan | Conquest of Romania by Central Powers. (Details) |
| August 27 – November 26 | Balkan | Battle of Transylvania, a phase of the conquest of Romania. |
| August 28 | Politics | Italy declares war on Germany. |
| August 29 | Politics | Paul von Hindenburg replaces Erich von Falkenhayn as German Chief of Staff. (Details) |
| August 30 | Politics | The Ottoman Empire declares war on Romania. |
| September 1 | Politics | Bulgaria declares war on Romania. |
| September 2–6 | Balkan | Battle of Turtucaia, a phase of the conquest of Romania. |
| September 3–6 | Western | Battle of Guillemont (intermediate phase of the Battle of the Somme) (Details) |
| September 5–7 | Balkan | Battle of Dobrich, a phase of the conquest of Romania. |
| September 6 | Politics | The Central Powers create a unified command. |
| September 7–11 | African | Battle of Kisaki. |
| September 8–19 | African | Battle of Tabora. |
| September 9 | Western | Battle of Ginchy (intermediate phase of the Battle of the Somme) (Details) |
| September 9–11 | African | Battle of Dutumi. |
| September 12 – December 11 | Balkan | Monastir Offensive, set up of the Salonika front. |
| September 12–14 | Balkan | Battle of Malka Nidzhe, a phase of the Monastir Offensive. |
| September 12–30 | Balkan | Battle of Kaymakchalan, a phase of the Monastir Offensive. |
| September 14–17 | Italian | Seventh Battle of the Isonzo |
| September 15–22 | Western | Battle of Flers-Courcelette; the British use armoured tanks for the first time in history. (Details) |
| September 17–19 | Balkan | First Battle of Cobadin, a phase of the conquest of Romania. |
| September 20 | Eastern | The Brusilov Offensive ends with a substantial Russian success. (Details) |
| September 25–28 | Western | Battle of Morval (part of the final stages of the Battle of the Somme) (Details) |
| September 26–28 | Western | Battle of Thiepval Ridge (part of the final stages of the Battle of the Somme) (Details) |
| September 29 – October 5 | Balkan | Flamanda Offensive, a phase of the conquest of Romania. |
| October–November | Balkan | First Battle of the Cerna Bend, a phase of the Monastir Offensive. (Details) |
| October 1 – November 5 | Western | Battle of Le Transloy (last stage of the Battle of the Somme) (Details) |
| October 1 – November 11 | Western | Battle of Ancre Heights (last stage of the Battle of the Somme). |
| October 9–12 | Italian | Eighth Battle of the Isonzo. |
| October 14 – January 6, 1917 | African | Battle of Kibata. |
| October 19–25 | Balkan | Second Battle of Cobadin, a phase of the conquest of Romania. |
| October 24 | Western | The French recapture Fort Douaumont near Verdun. (Details) |
| November 1–4 | Italian | Ninth Battle of the Isonzo. |
| November 11 | African | Battle of Matamondo. |
| November 13–18 | Western | Battle of the Ancre (closing phase of the Battle of the Somme) (Details) |
| November 18 | Western | The Battle of the Somme ends with enormous casualties and an Anglo-French advantage. (Details) |
| November 21 | Naval | HMHS Britannic sinks after hitting a German mine, becoming the largest ship lost during WW1. (Details) |
| November 21 | Politics | Francis Joseph I, Emperor of Austria and King of Hungary, dies and is succeeded by Charles I. (Details) |
| November 25 | Naval | David Beatty replaces John Jellicoe as commander of the Grand Fleet. Jellicoe becomes First Lord of the Sea. (Details) |
| November 25 – December 3 | Balkan | Battle of Bucharest, a phase of the conquest of Romania. |
| November 28 | Balkan | Prunaru Charge, a phase of the Battle of Bucharest, Romanian cavalry desperately charge into enemy lines. |
| December 1 | Balkan | Battle of the Arges, a phase of the Battle of Bucharest. |
| December 1 – January 18, 1917 | Middle Eastern | Allies capture Yanbu. (Details) |
| December 3–6 | Politics | In a four-day crisis December 3–6, 1916, H. H. Asquith is unaware how fast he is losing support. David Lloyd George now has growing Unionist support, the backing of Labour and (thanks to Christopher Addison) a majority of Liberal MPs. Asquith falls. (Details) |
| December 7–31 | Politics | The new Prime Minister Lloyd George answers the loud demands for a much more decisive government. He energetically sets up a new small war cabinet, a cabinet secretariat under Maurice Hankey, a secretariat of private advisors in the 'Garden Suburb' and moved towards prime ministerial control. (Details) |
| December 6 | Balkan | The Germans occupy Bucharest. The capital of Romania moved to Iaşi. (Details) |
| December 13 | Western | Robert Nivelle replaces Joseph Joffre as Commander-in-Chief of the French Army. (Details) |
| December 17 | African | Kaocen Revolt: The Tuareg besiege the French garrison at Agadez. |
| December 18 | Western | Battle of Verdun ends with enormous casualties on both sides. |
| December 23 | Middle Eastern | Battle of Magdhaba in the Sinai peninsula. (Details) |
| December 23–29 | Eastern | Christmas Battles. |
| December 27 | African | Togoland is divided into British and French administrative zones. (Details) |
| December 30 | Politics | Grigori Rasputin, Russia's éminence grise, is assassinated. (Details) |

## 1917

| Dates | Theater/Front/Campaign | Events |
| January 3–4 | African | Battle of Behobeho. |
| January 9 | Middle Eastern | Battle of Rafa. The British drive the Ottomans out of Sinai. (Details) |
| January 11 – March 13 | Western | British raid the Ancre. (Details) |
| January 16 | Politics | The German Foreign Secretary Arthur Zimmermann sends a telegram to his ambassador in Mexico, instructing him to propose an alliance against the United States to the Mexican government. (Details) |
| February 1 | Naval | Germany resumes unrestricted submarine warfare. (Details) |
| February 3 | Naval | SS Housatonic an American steamer carrying wheat from Galveston, Texas to England is sunk by a U-boat. |
| February 13 | Politics | Mata Hari is arrested in Paris on charges of spying for the Germans. |
| February 21 | Western | Sinking of the SS Mendi-the SS Mendi was a troop ship carrying members of the South African Native Corps (SANLC).The SANLC was a group of black South Africans recruited as non-combatants. The ship was on its way to France where the SANLC members were going to the trenches on the Western Front. The Mendi stopped in England and was heading across the English Channel when it sank |
| February 23 | Middle Eastern | Second Battle of Kut. The British recapture the city. (Details) |
| February 23 – April 5 | Western | The Germans withdraw to the Hindenburg Line. |
| March 1 | Politics | Arz von Straussenberg replaces Conrad von Hötzendorf as Austro-Hungarian Chief of Staff. (Details) |
| March 3 | African | The French relieve Agadez. |
| March 8–11 | Middle Eastern | The British capture Baghdad. (Details) |
| March 8 | Politics | The celebrations of International Women's Day in Petrograd spawn severe protests that will evolve into the February Revolution. |
| March 12 | Politics | Russian troops refuse to fire on demonstrators after 50 are killed in Petrograd's Znamenskaya Square the day before. Numerous attacks against prisons, courts, police stations and Okhrana offices. Provisional Committee of the Duma formed. Petrograd Soviet formed. |
| March 13 | African | Battle of Nambanje. |
| March 13 – April 23 | Middle Eastern | Samarra offensive, British capture much of Mesopotamia. |
| March 14 | Politics | China severs relations with Germany. |
| March 15 | Politics | Nicholas II abdicates. A provisional government is formed. |
| March 16 | Politics | Lenin arrives in Petrograd from his exile in Switzerland and publishes his April Thesis. |
| March 17 | Politics | Aristide Briand resigns as Prime Minister of France; he is replaced by Alexandre Ribot. |
| March 26 | Middle Eastern | First Battle of Gaza. The British attempt to capture the city fails. (Details) |
| April–October | Middle Eastern | Stalemate in Southern Palestine. |
| April 2–3 | Western | Australians attack Noreuil. (Details.) |
| April 6 | Politics | The United States declares war on Germany. (Details) |
| April 7 | Politics | Cuba declares war on Germany. |
| April 7 | Politics | Panama declares war on Germany. |
| April 7 | Asian and Pacific | Scuttling of SMS Cormoran in Guam, the only hostile action between American and German forces in the Pacific. |
| April 9 – May 17 | Western | Second Battle of Arras. The British attack a heavily fortified German line without obtaining any strategic breakthrough. (Details) |
| April 9–12 | Western | The Canadians obtain a significant victory in the Battle of Vimy Ridge, part of the first phase of the Second Battle of Arras. (Details) |
| April 9–14 | Western | First Battle of the Scarpe, part of the first phase of the Second Battle of Arras. (Details) |
| April 10–11 | Western | First Battle of Bullecourt, part of the first phase of the Second Battle of Arras. (Details) |
| April 11 | Politics | Brazil severs relations with Germany. |
| April 13 | Politics | Bolivia severs relations with Germany. |
| April 15 | Western | Battle of Lagnicourt, part of the Second phase of the Second Battle of Arras. (Details) |
| April 16 – May 9 | Western | The Second Battle of the Aisne (also known as Nivelle Offensive) ends in disaster for both the French army and its commander Robert Nivelle. (Details) |
| April 17–20 | Western | Battle of the Hills (also known as Third battle of Champagne), a diversion to the Second Battle of the Aisne. |
| April 19 | Middle Eastern | Second Battle of Gaza. The Ottoman lines resist a British attack. (Details) |
| April 22 – May 8 | Balkan | Second Battle of Doiran. (Details) |
| April 23 | Politics | The Ottoman Empire severs relations with the United States. |
| April 23–24 | Western | Second Battle of Scarpe, part of the second phase of the Second Battle of Arras. (Details) |
| April 28–29 | Western | Battle of Arleux, part of the Second phase of the Second Battle of Arras. (Details) |
| April 29 – May 20 | Western | Series of mutinies in the French army. (Details) |
| May 3–4 | Western | Third battle of the Scarpe, part of the second phase of the Second Battle of Arras. (Details) |
| May 3–4 | Politics | Mass demonstrations in Petrograd and Moscow to protest Pavel Milyukov's note affirming Russia's commitment to the Entente war effort. (Details) |
| May 3–17 | Western | Second Battle of Bullecourt, part of the second phase of the Second Battle of Arras. (Details) |
| May 5 | Politics | Australian Prime Minister Billy Hughes wins an enlarged majority in federal elections with the pro-conscription Nationalist Party. (Details) |
| May 5–15 | Balkan | Allied Spring offensive on the Salonika front. |
| May 5–9 | Balkan | Second Battle of the Cerna Bend, a phase of the Allied Spring Offensive. (Details) |
| May 12 – June 6 | Italian | Tenth Battle of the Isonzo. (Details) |
| May 15 | Western | Philippe Pétain replaces Robert Nivelle as Commander-in-Chief of the French Army. (Details) |
| May 23 | Italian | Battle of Mount Hermada in the Karst. |
| May 23 | Politics | Salonika Trial ends: Dragutin Dimitrijevic, chief conspirator of the Sarajevo Assassination, is sentenced to death by Serbia on trumped up charges, as part of negotiations for a peace treaty with Austria-Hungary. |
| June–October | Western | Operation Hush, Abortive British plan to capture coast of Belgium. |
| June 7–14 | Western | Second Battle of Messines, the British blow 19 deep mines and recapture Messines Ridge. (Details) |
| June 10–29 | Italian | Battle of Mount Ortigara. (Details) |
| June 12 | Politics | Constantine I of Greece abdicates. |
| June 13 | Air | First successful heavy bomber raid on London done by the Gotha G.IV. |
| June 25 | Western | First American troops land in France. (Details) |
| June 27 | Western | Batterie Pommern aka. 'Lange Max', world's largest gun fires for the first time from Koekelare to Dunkirk (±50 km). |
| June 30 | Politics | Greece declares war on the Central powers. (Details) |
| July 1–2 | Eastern | Battle of Zborov, a phase of the Kerensky Offensive. (Details) |
| July 1–12 | Politics | Brief monarchist coup and restoration in China, allegedly promoted by Germany to distance China from the Entente. (Details) |
| July 1–19 | Eastern | The Kerensky Offensive fails. It is the last Russian initiative in the war. (Details) |
| July 6 | Middle Eastern | Arab rebels led by Lawrence of Arabia seize the Jordanian port of Aqaba. (Details) |
| July 11 | Western | The Open Letter to Albert I is published by Flemish Movement sympathisers within the Belgian Army on the Yser Front, complaining about official discrimination against Dutch language (Details) |
| July 16–17 | Politics | Petrograd July Days. |
| July 19 | Politics | The Reichstag passes a Peace Resolution. |
| July 20 | Politics | Corfu Declaration about the future Kingdom of Yugoslavia. (Details) |
| July 21 | Politics | Alexander Kerensky replaces Georgy Lvov as Minister-President of the Russian Provisional Government. |
| July 22 | Politics | Siam declares war on Germany and Austria-Hungary. |
| July 22 – August 1 | Balkan | Battle of Mărăști |
| July 29 | African | Battle of Kiawe Bridge. |
| July 31 | Western | The Third Battle of Ypres (also known as Battle of Passchendaele) begins. (Details) |
| July 31 – August 2 | Western | Battle of Pilckem Ridge (Opening phase of the Third Battle of Ypres). |
| August 2 | Asian and Pacific | The German raider SMS Seeadler is wrecked at Mopelia in French Polynesia. |
| August 2–10 | African | Battle of Rumbo. |
| August 4 | Politics | Liberia declares war on Germany. |
| August 6–20 | Balkan | Battle of Mărăşeşti. (Details) |
| August 8–22 | Balkan | Third Battle of Oituz. |
| August 14 | Politics | China declares war on Germany and Austria-Hungary. |
| August 15–25 | Western | Battle of Hill 70 (Continuation of British operations near Lens). |
| August 16–18 | Western | Second Battle of Langemarck (Initial phase of the Third Battle of Ypres). (Details) |
| August 17 | Asian and Pacific | China terminates the German and Austro-Hungarian concessions in Tianjin and occupies them. |
| August 18–28 | Italian | Eleventh Battle of the Isonzo. (Details) |
| August 20–26 | Western | Second Offensive Battle of Verdun. |
| September – October | Eastern | Operation Albion. German capture of Oesel, Dago and Moon Islands. |
| September 1–3 | Eastern | Battle of Jugla. |
| September 5 | Asian and Pacific | The SMS Seeadler's crew sail to Fiji in a lifeboat and capture the French schooner Lutece, allowing their escape. They rename it Fortuna. |
| September 5–12 | Politics | The Third Zimmerwald Conference of the anti-war socialist Zimmerwald Movement, is held in Stockholm. (Details) |
| September 8–12 | Politics | Russia: General Kornilov's coup attempt fails. (Details) |
| September 12 | Politics | Alexandre Ribot resigns as Prime Minister of France; he is replaced by Paul Painlevé. |
| September 14 | Politics | Russia declared a republic. |
| September 20–26 | Western | Battle of the Menin Road Ridge (Second phase of the Third Battle of Ypres). |
| September 21 | Politics | Costa Rica severs relations with Germany. |
| September 26–27 | Western | Battle of Polygon Wood (Second phase of the Third Battle of Ypres). |
| September 28–29 | Middle Eastern | Battle of Ramadi, Mesopotamia. (Details) |
| October 4 | Western | Battle of Broodseinde (Second phase of the Third Battle of Ypres). |
| October 5 | Asian and Pacific | The Fortuna wrecks at Easter Island and its crew is interned by the Chileans. |
| October 6 | Politics | Peru severs relations with Germany. |
| October 7 | Politics | Uruguay severs relations with Germany. |
| October 9 | Western | Battle of Poelcappelle (Last phase of the Third Battle of Ypres). |
| October 12 | Western | First Battle of Passchendaele (Last phase of the Third Battle of Ypres). |
| October 15 | Politics | Mata Hari executed. |
| October 15–18 | African | Battle of Mahiwa. |
| October 23 | Middle Eastern | Battle of Wadi Musa. |
| October 23 – November 10 | Western | Battle of La Malmaison, much-postponed French attack on the Chemin des Dames. (Details) |
| October 24 – November 4 | Italian | Battle of Caporetto. The Austro-Hungarians and Germans break through the Italian lines. The Italian army is defeated and falls back on the Piave River. (Details) |
| October 26 | Politics | Brazil declares war on Germany. |
| October 26 – November 10 | Western | Second Battle of Passchendaele (Last phase of the Third Battle of Ypres). |
| October 27 | Middle Eastern | Battle of Buqqar Ridge. |
| October 30 | Politics | Italy: Vittorio Emanuele Orlando succeeds Paolo Boselli as Prime Minister. (Details) |
| October 31 – November 7 | Middle Eastern | Third Battle of Gaza. The British break through the Ottoman lines. (Details) |
| October 31 | Middle Eastern | Battle of Beersheba (opening phase of the Third Battle of Gaza). (Details) |
| November 1–6 | Middle Eastern | Battle of Tel el Khuweilfe. |
| November 2 | Politics | Balfour Declaration: the British government supports plans for a Jewish "national home" in Palestine. (Details) |
| November 5 | Politics | The Allies agree to establish a Supreme War Council at Versailles. |
| November 7 | Politics | October Revolution: Kerensky flees Petrograd just before the Petrograd Soviet seizes the Winter Palace. |
| November 7 | Middle Eastern | Charge at Sheria. |
| November 8 | Italian | Armando Diaz replaces Luigi Cadorna as Commander-in-Chief of the Italian Army. (Details) |
| November 8 | Middle Eastern | Charge at Huj. |
| November 9 – December 28 | Italian | First Battle of the Piave: the Austro-Hungarians and Germans try unsuccessfully to cross the river. (Details) |
| November 10 | Western | The Third Battle of Ypres (also known as Battle of Passchendaele) ends. (Details) |
| November 11 – December 23 | Italian | First Battle of Monte Grappa, Austro-Hungarian offensive halted. |
| November 13 | Politics | France: Paul Painlevé is replaced by Georges Clemenceau as Prime Minister. (Details) |
| November 13 | Middle Eastern | Battle of Mughar Ridge. |
| November 14 | Middle Eastern | Battle of Ayun Kara. |
| November 17 | Naval | Second Battle of Heligoland Bight, North Sea. (Details) |
| November 17 – December 30 | Middle Eastern | Battle of Jerusalem. The British enter the city (December 11). (Details) |
| November 18–24 | Middle Eastern | Battle of Nebi Samwil, a phase of the Battle of Jerusalem. |
| November 19 | Italian | Battle of Caporetto ends. Central Powers take a quarter of a million prisoners. (Details) |
| November 20 – December 3 | Western | First Battle of Cambrai. A British attack and the biggest German attack against the British since 1915 succeed and the battle is a stalemate. (Details) |
| November 25 | African | Battle of Ngomano, the Germans invade Portuguese East Africa to gain supplies. |
| December 1 | Middle Eastern | Battle of El Burj, a phase of the Battle of Jerusalem. |
| December 6 | Naval | Halifax Explosion: An accidental collision between the Norwegian supply ship SS Imo and the French cargo ship SS Mont-Blanc, laden with high explosives for the Western Front, leaves 2,000 dead and 9,000 injured in Richmond, Nova Scotia. It is the largest man-made explosion before the invention of atomic weapons. |
| December 6 | Politics | Finland declares independence from Russia. |
| December 7 | Politics | The United States declares war on Austria-Hungary. |
| December 8 | Politics | Ecuador severs relations with Germany. |
| December 9 | Politics | Romania signs an armistice with the Central Powers. |
| December 10 | Politics | Panama declares war on Austria-Hungary. |
| December 11 | Middle Eastern | General Allenby leads British and Indian troops into Jerusalem, ending 400 years of Ottoman rule. |
| December 15 | Politics | Armistice between Russia and the Central Powers, to take effect on December 17. |
| December 16 | Politics | Armistice of Erzincan between the Ottomans and the Russian Special Transcaucasian Committee. |
| December 17 | Politics | Canadian Prime Minister Robert Borden wins an enlarged majority in federal elections with the pro-conscription Unionist Party. (Details) |
| December 20–21 | Middle Eastern | Battle of Jaffa, a phase of the Battle of Jerusalem. (Details) |

## 1918

| Dates | Theater/Front/Campaign | Events |
| January 8 | Politics | Woodrow Wilson outlines his Fourteen Points. (Details) |
| February to September | Middle Eastern | Allied forces occupy the Jordan Rift Valley. (Details) |
| February 9 | Politics | The Central Powers sign an exclusive protectorate treaty with the Ukrainian People's Republic as part of the negotiations in Brest-Litovsk. (Details) |
| February 15–16 | Eastern | Battle of Rarancza. |
| February 18 – March 3 | Eastern | Operation Faustschlag, last offensive on Eastern Front. |
| February 19 | Middle Eastern | British begin their assault on Jericho. (Details) |
| February 21 | Middle Eastern | The British capture Jericho. (Details) |
| February 21 | Eastern | Germans capture Minsk. (Details) |
| February 24 | Eastern | Germans capture Zhytomyr. (Details) |
| February 25 | Eastern | German troops capture Tallinn. (Details) |
| February 28 | Eastern | Germans capture Pskov and Narva. (Details) |
| March 2 | Eastern | Germans capture Kiev. (Details) |
| March 3 | Politics | At Brest-Litovsk, Leon Trotsky signs the peace treaty with Germany. (Details) |
| March 4 | | First known case of what will later be called Spanish flu: Private Albert Gitchell at Camp Funston, Fort Riley, Kansas. |
| March 7 | Western | German artillery bombard the Americans at Rouge Bouquet. (Details) |
| March 8–12 | Middle Eastern | Battle of Tell 'Asur. |
| March 8–13 | Eastern | Battle of Bakhmach. |
| March 11 | | Over 100 sick from Spanish flu in Fort Riley; first known case outside in Queens, New York. |
| March 21 – April 5 | Western | First phase of the German spring offensive, Operation Michael (also known as Second Battle of the Somme). The Germans obtain a Pyrrhic victory. (Details) |
| March 21–23 | Western | The Battle of St. Quentin, first phase of Operation Michael and the Spring Offensive. (Details) |
| March 21 – April 2 | Middle Eastern | First Transjordan attack on Amman. |
| March 23 – August 7 | Western | Artillery bombardment of Paris. (Details) |
| March 24–25 | Western | First Battle of Bapaume, a phase of Operation Michael. (Details) |
| March 25 | Western | First Battle of Noyon, a phase of Operation Michael. (Details) |
| March 25 | Politics | Penza Agreement: The Czechoslovak Legion is given free passage to Vladivostok to join the Entente in return for surrendering most weapons to the Bolsheviks. |
| March 26 | Politics | French Marshal Ferdinand Foch is appointed Supreme Commander of all Allied forces. (Details) |
| March 26–27 | Western | Battle of Rosieres, a phase of Operation Michael. (Details) |
| March 26–27 | Middle Eastern | Action of Khan Baghdadi. |
| March 27–31 | Middle Eastern | First Battle of Amman, a phase Of The First Transjordan Attack. |
| March 28 | Western | Third Battle of Arras (also known as First Battle of Arras (1918)), a phase of Operation Michael. (Details) |
| March 30 – April 5 | Western | First Battle of Villers-Bretonneux, a phase of Operation Michael. |
| March 30 | Western | Battle of Moreuil Wood. |
| April 1 | Air | Royal Air Force founded by combining the Royal Flying Corps and the Royal Naval Air Service. |
| April 4–5 | Western | Battle of the Avre, final phase of Operation Michael. |
| April 7–29 | Western | Second phase of the Spring Offensive, Operation Georgette (also known as Battle of the Lys). The results are disappointing for the Germans. (Details) |
| April 7–9 | Western | Battle of Estaires, first phase of Operation Georgette. (Details) |
| April 10–11 | Western | Third Battle of Messines, a phase of Operation Georgette. (Details) |
| April 12–13 | Western | Battle of Hazebrouck, a phase of Operation Georgette. (Details) |
| April 13–15 | Western | Battle of Bailleul, a phase of Operation Georgette. (Details) |
| April 14 | Politics | Ottokar Czernin resigns as Austria-Hungary's Foreign Minister over the Sixtus Affair. |
| April 17–19 | Western | First Battle of Kemmelberg, a phase of Operation Georgette. (Details) |
| April 18 | Western | Battle of Bethune, a phase of Operation Georgette. (Details) |
| April 21 | Air | The Red Baron is shot down over Vaux-sur-Somme. |
| April 23 | Politics | Guatemala declares war on Germany. |
| April 24–27 | Western | Second Battle of Villers-Bretonneux, a phase of Operation Georgette. |
| April 25–26 | Western | Second Battle of Kemmelberg, a phase of Operation Georgette. (Details) |
| April 28 | Politics | Gavrilo Princip dies in Terezín prison, from tuberculosis. |
| April 29 | Western | Battle of Scherpenberg, final phase of Operation Georgette. (Details) |
| April 30 – May 4 | Middle Eastern | Second Transjordan attack on Shunet Nimrin and Es Salt. |
| May 7 | Politics | Treaty of Bucharest between Romania and the Central Powers. It will never be ratified. (Details) |
| May 8 | Politics | Nicaragua declares war on Germany and Austria-Hungary. |
| May 10–11 | Eastern | Battle of Kaniow. |
| May 14 | Politics | Clash at Chelyabinsk station between Hungarian POWs heading west to be repatriated and Czechoslovaks going east. Trotsky orders the arrest of the Czechoslovak Legion, but they revolt and seize several towns along the Trans-Siberian Railway. (Details) |
| May 21 | Caucasian | Ottomans invade Armenia. (Details) |
| May 21–29 | Caucasian | Battle of Sardarabad, a phase of the invasion of Armenia. |
| May 21–29 | Caucasian | Battle of Abaran, a phase of the invasion of Armenia. |
| May 23 | Politics | Costa Rica declares war on Germany. |
| May 24–28 | Caucasian | Battle of Karakilisa, a phase of the invasion of Armenia. |
| May 27 – June 6 | Western | Third Battle of the Aisne (also known as Operation Blücher-Yorck, third phase of the Spring Offensive). After initial gains, the German advance is halted. (Details) |
| May 28 | Western | Battle of Cantigny. |
| May 29–31 | Balkan | Battle of Skra-di-Legen |
| June 1–26 | Western | Battle of Belleau Wood, part of the German spring offensive. |
| June 8 | Middle Eastern | Action of Arsuf. |
| June 8 | Caucasian | Ottomans re-enter Tabriz. (Details) |
| June 8 | Politics | The Czechoslovak Legion forms the Committee of Members of the Constituent Assembly in Samara. Stanislav Čeček calls to join forces with anti-Bolshevik Russians to overthrow the Communist government and reignite the Eastern Front. (Details) |
| June 8 – October | Caucasian | Germany interferes in the Caucasus. (Details) |
| June 9–12 | Western | Fourth phase of the Spring Offensive, Operation Gneisenau (also known as Battle of Matz). Despite substantial territorial gains, the Germans do not achieve their strategic goals (Details) |
| June 13 | Politics | Provisional Siberian Government formed in Omsk. |
| June 15–23 | Italian | Second Battle of the Piave: the Austro-Hungarian offensive is repelled. (Details) |
| June 15–31 | Caucasian | Ottomans occupy Dilman, Khoy and Urmia. (Details.) |
| June 23 | Eastern | British and French troops land at Murmansk in Northern Russia. It's the beginning of Allied Intervention in the Russian Civil War on the White Army's side. (Details.) |
| July 4 | Western | Battle of Hamel. |
| July 12 | Politics | Haiti declares war on Germany. |
| July 14 | Middle Eastern | Battle of Abu Tellul. |
| July 15 – August 6 | Western | Second Battle of the Marne and last German offensive on the Western Front, which fails when the Germans are counterattacked by the French. (Details) |
| July 15–17 | Western | Champagne-Marne Offensive (consisting of the Fourth Battle of Champagne and the Battle of the Mountain of Reims), a phase of the Second Battle of the Marne. last phase of the Spring Offensive and last German offensive of World War I. (Details) |
| July 17 | Politics | Nicholas II and his family are executed by the Bolsheviks, out of fear that they might be released by Czechoslovak and White troops. (Details) |
| July 18 | Western | Battle of Chateau-Thierry, a phase of the Second Battle of the Marne. (Details) |
| July 18 | Western | End of the Second Battle of Artois |
| July 18–22 | Western | Battle of Soissons, a phase of the Second Battle of the Marne. (Details) |
| July 19 | Western | Battle of Tardenois, a phase of the Second Battle of the Marne. |
| July 19 | Politics | Honduras declares war on Germany. |
| August | | Spanish flu virus mutates: Simultaneous deadlier outbreaks in Brest, Freetown and Boston. |
| August 5 | Eastern | The Czechoslovak People's Army of Komuch takes Kazan from the Bolsheviks and captures the Imperial Russian gold reserve. (Details) |
| August 8 – November 11 | Western | Hundred Days Offensive, last offensive on Western Front. |
| August 8–12 | Western | Battle of Amiens, first phase of the Hundred Days Offensive. (Details) |
| August 9–12 | Western | Battle of Montdidier. |
| August 13 – September 3 | Italian | Battle of San Matteo. |
| August 17–29 | Western | Second Battle of Noyon, a phase of the Hundred Days Offensive. (Details) |
| August 21–22 | Western | Third Battle of Albert, opening phase of the Second Battle of the Somme. (Details) |
| August 21 – September 3 | Western | Second Battle of the Somme (also known as Third battle of the Somme), a phase of the Hundred Days Offensive. (Details) |
| August 21 – September 3 | Western | Second Battle of Bapaume, a phase of the Second Battle of the Somme. |
| August 26 – September 3 | Western | Fourth Battle of Arras (also known as Second Battle of Arras (1918)), a phase of the Second Battle of the Somme (Details) |
| August 26–30 | Western | Fourth Battle of the Scarpe (also known as Battle of the Scarpe (1918)), a phase of the Fourth Battle of Arras. (Details) |
| August 26 – September 14 | Caucasian | Battle of Baku, last Turkish offensive of the war. |
| August 30–31 | African | Battle of Lioma. |
| August 31 – September 3 | Western | Battle of Mont Saint-Quentin, a phase of the Second Battle of the Somme. |
| September 1–2 | Western | Battle of Peronne, a phase of the Battle of Mont Saint-Quentin. (Details) |
| September 2–3 | Western | Battle of Drocourt-Queant Line, final phase of the Second Battle of the Somme. (Details) |
| September 8–23 | Politics | Ufa Conference: Formation of the Provisional All-Russian Government with the support of the Czechoslovak Legion. |
| September 10 | Western | Battle of Savy-Dallon, a phase of the Hundred Days Offensive. (Details) |
| September 12 | Western | Battle of Havrincourt, a phase of the Hundred Days Offensive. (Details) |
| September 12–15 | Western | Battle of Saint-Mihiel, a phase of the Hundred Days Offensive. |
| September 14 | Western | Battle of Vauxaillon, a phase of the Hundred Days Offensive. (Details) |
| September 14–29 | Balkan | Vardar Offensive, final offensive on the Balkan Front. |
| September 15 | Balkan | The Allies (French and Serbs) break through the Bulgarian lines at Dobro Polje, a phase of the Vardar Offensive. (Details) |
| September 18 | Western | Battle of Epehy, a phase of the Hundred Days Offensive. |
| September 18–19 | Balkan | Third Battle of Doiran, a phase of the Vardar Offensive, The Bulgarians halt the British and Greek advance. (Details) |
| September 18 – October 17 | Western | Battle of the Hindenburg Line, a phase of the Hundred Days Offensive. The Allies break through the German lines. (Details) |
| September 19–25 | Middle Eastern | Battle of Megiddo. The British conquer Palestine. (Details) |
| September 19–25 | Middle Eastern | Battle of Nablus, a phase of the Battle of Meggido. (Details) |
| September 19–25 | Middle Eastern | Third Transjordan attack, a phase of the Battle of Nablus. |
| September 19–25 | Middle Eastern | Battle of Sharon, a phase of the Battle of Megiddo. |
| September 19 | Middle Eastern | Battle of Tulkarm, a phase of the Battle of Sharon. |
| September 19 | Middle Eastern | Battle of Arara, a phase of the Battle of Sharon. |
| September 19–20 | Middle Eastern | Battle of Tabsor, a phase of the Battle of Sharon. |
| September 20 | Middle Eastern | Capture of Jenin, a phase of the Battle of Sharon. |
| September 20 | Middle Eastern | British capture both Afulah and Beisan during the Battle of Sharon. (Details) |
| September 20–21 | Middle Eastern | Battle of Nazareth, a phase of the Battle of Sharon. |
| September 22 | Middle Eastern | The British capture Jisr ed Damieh in the Battle of Sharon. (Details) |
| September 23 | Middle Eastern | Battle of Haifa, a phase of the Battle of Sharon. (Details) |
| September 25 | Middle Eastern | Battle of Samakh, a phase of the Battle of Sharon. |
| September 25 | Middle Eastern | The British capture Tiberias during the Battle of Sharon. (Details) |
| September 25 | Middle Eastern | Second Battle of Amman, a phase of the Third Transjordan Attack. |
| September 26 – November 11 | Western | Meuse-Argonne Offensive, the final phase of the Hundred Days Offensive and of World War I. (Details) |
| September 26 – October 1 | Middle Eastern | The British enter Damascus. (Details) |
| September 26 | Western | Battle of Somme-Py (Initial phase of the Meuse-Argonne Offensive). (Details) |
| September 26 | Middle Eastern | Charge at Irbid, a phase of the Capture of Damascus. |
| September 26–27 | Middle Eastern | British capture Deraa during the Capture of Damascus. (Details) |
| September 27 | Middle Eastern | Battle of Jisr Benat Yakub, a phase of the Capture of Damascus. |
| September 27 – October 1 | Western | Battle of the Canal du Nord, a phase of the Battle of the Hindenburg Line. |
| September 28 – October 2 | Western | Fifth Battle of Ypres (also known as Advance on Flanders), a phase of the Battle of the Hindenburg Line. |
| September 29 – October 10 | Western | Battle of St. Quentin Canal, a phase of the Hundred Days Offensive. |
| September 30 | Politics | Bulgaria signs an armistice with the Allies. |
| September 30 | Western | Battle of Saint-Thierry (Initial phase of the Meuse-Argonne Offensive). (Details) |
| September 30 | Middle Eastern | Charge at Kaukab, a phase of the Capture of Damascus. |
| September 30 | Middle Eastern | Charge at Kiswe, a phase of the Capture of Damascus. |
| October 3 | Politics | Tsar Ferdinand I of Bulgaria abdicates and Boris III accedes to the throne. |
| October 3–27 | Middle Eastern | Pursuit to Haritan. |
| October 3–27 | Western | Battle of Blanc Mont Ridge. |
| October 4 | Politics | Germany requests an Armistice to U.S. President Woodrow Wilson. He demands German withdrawal from all occupied territory, and the Kaiser's abdication. |
| October 8–10 | Western | Second Battle of Cambrai (also known as Battle of Cambrai (1918)), a phase of the Battle of the Hindenburg Line. (Details) |
| October 14–17 | Western | Battle of Montfaucon (intermediate phase of the Meuse-Argonne Offensive). (Details) |
| October 14–19 | Western | Battle of Courtrai, closing phase of the Hundred Days offensive. (Details) |
| October 15 | Western | Battle of Mont-D'Origny, a phase of the Hundred Days Offensive. (Details) |
| October 17–26 | Western | Battle of the Selle, closing phase of the Hundred Days Offensive. |
| October 20 | Naval | Germany suspends submarine warfare. (Details) |
| October 20 | Western | Battle of Lys and Escaut (Which included the Second Battle of Lys and the Battle of the Escaut), a phase of the Hundred Days Offensive. (Details) |
| October 20 | Western | Battle of Serre, a phase of the Hundred Days Offensive. (Details) |
| October 23–30 | Middle Eastern | Battle of Sharqat. |
| October 24 – November 4 | Italian | Battle of Vittorio Veneto. The Austro-Hungarian army is routed. The Italians enter Trent and land at Triest. (Details) |
| October 24–28 | Italian | Second Battle of Monte Grappa, beginning phase of Vittorio Veneto. |
| October 25 | Middle Eastern | Battle of Aleppo. (Details) |
| October 29 | Politics | Wilhelm Groener replaces Erich Ludendorff as Hindenburg's deputy. (Details) |
| October 29 | Naval | Germany's Hochseeflotte mutinies. (Details) |
| October 29 | Politics | State of Slovenes, Croats and Serbs proclaimed. (Details) |
| October 30 | Politics | The Ottoman Empire signs the Armistice of Mudros. (Details) |
| November | | First Spanish flu cases in Spain, where reports on the disease are published freely due to the lack of wartime censorship. |
| November 1 | Western | Battle of Chesne (Closing phase of the Meuse-Argonne Offensive). (Details) |
| November 1–2 | Western | Battle of Valenciennes, closing phase of the Hundred Days Offensive. (Details) |
| November 3 | Politics | Austria-Hungary signs the armistice with Italy, effective November 4. |
| November 4 | Western | Battle of the Sambre, closing phase of the Hundred Days Offensive. (Details) |
| November 4 | Western | Second Battle of Guise, a phase of the Battle of Sambre. (Details) |
| November 4 | Western | Battle of Thierache, a phase of the Battle of Sambre. (Details) |
| November 6–11 | Western | Advance to the Meuse. |
| November 9 | Politics | Germany: Kaiser William II abdicates; republic proclaimed. (Details) |
| November 10 | Politics | Austria-Hungary: Kaiser Charles I abdicates. (Details) |
| November 10 | Balkan | Romania renews the war against the Central Powers. |
| November 11 | Politics | At 6 am, Germany signs the Armistice of Compiègne. End of fighting at 11 a.m.. (Details) |
| November 11 | Politics | Poland proclaimed. |
| November 12 | Politics | Austria proclaimed a republic. |
| November 14 | Politics | Czechoslovakia proclaimed a republic. (Details) |
| November 14 | Naval | German U-boats interned. |
| November 14 | African | Three days after the armistice, fighting ends in the East African theatre when General von Lettow-Vorbeck agrees a cease-fire on hearing of Germany's surrender. (Details) |
| November 18 | Politics | Alexander Kolchak seizes control of the Provisional All-Russian Government in a coup. |
| November 21 | Naval | Germany's Hochseeflotte surrendered to the United Kingdom. (Details) |
| November 22 | Western | The Germans evacuate Luxembourg. |
| November 25 | African | 11 days after agreeing a cease-fire, General von Lettow-Vorbeck formally surrenders his undefeated army at Abercorn in present-day Zambia. (Details) |
| November 27 | Western | The Germans evacuate Belgium. |
| December 1 | Politics | Kingdom of Serbs, Croats and Slovenes proclaimed. (Details) |

## 1919

| Dates | Theater/Front/Campaign | Events |
| January 5 | Asian and Pacific | Hermann Detzner surrenders at the Finschhafen District of New Guinea. |
| January 10 | Middle Eastern | Fakhri Pasha surrenders at Medina. (Details) |
| January 18 | Politics | Treaty of Versailles between the Allies and Germany: the Peace Conference opens in Paris. (Details) |
| January 25 | Politics | Proposal to create the League of Nations accepted. (Details) |
| January 27 | Politics | The Czechoslovak Legion assumes complete control of the Trans-Siberian Railway. |
| June 21 | Naval | German High Seas Fleet (53 ships) scuttled in Scapa Flow with nine deaths, the last casualties of the war. (Details) |
| June 28 | Politics | Treaty of Versailles signed. (Details) |
| July 8 | Politics | Germany ratifies the Treaty of Versailles. (Details) |
| July 21 | Politics | The United Kingdom ratifies the Treaty of Versailles. (Details) |
| November 10–11 | Politics | A Banquet in Honour of The President of the French Republic is hosted by King George V and held at Buckingham Palace during the evening hours of November 10. The very first Armistice Day is held on the Grounds of Buckingham Palace on the Morning of November 11. This will set the trend for the later Remembrance Day. (Details) |
| November 14 | Politics | The Bolsheviks take Omsk. Kolchak's retreat east is impeded by the Czechoslovaks denying him use of the Trans-Siberian. |

## 1920

| Dates | Theater/Campaign/Front | Events |
| January 4 | Politics | A coup in Irkutsk deposes Kolchak. (Details) |
| January 10 | Politics | First meeting of the League of Nations held in London. (Details) |
| January 10 | Politics | Free City of Danzig established. (Details) |
| January 20 | Politics | Irkutsk surrenders to the Bolsheviks. |
| January 21 | Politics | The Paris Peace Conference ends. (Details) |
| February 7 | Politics | Armistice between the Bolsheviks and the Czechoslovak Legion. The Czechoslovaks surrender the Russian gold reserves and Kolchak in return for free passage to Vladivostok. Kolchak and his Prime Minister, Viktor Pepelyayev are executed. |
| February 10 | Politics | A plebiscite returns Northern Schleswig to Denmark. (Details) |
| April 19–26 | Politics | Conference of Sanremo, Italy, about League of Nations mandates in former Ottoman territories of the Middle East. (Details) |
| June 4 | Politics | Treaty of Trianon between the Allies and Hungary. (Details) |
| August 10 | Politics | Treaty of Sèvres between the Allies and the Istanbul Government of Ottoman Empire against objections of Turkish National Assembly. Eventually the treaty is not approved by Turkish National Assembly. Istanbul government was considered illegitimate by the Turkish national movement and Turkish National Assembly since Istanbul was occupied, Chamber of Deputies was raided, deputies were taken prisoner at Malta by allies at that time. (Details) |
| September 8 | Politics | Gabriele D'Annunzio proclaims in Fiume the Italian Regency of Carnaro. (Details) |
| November 1 | Politics | League of Nations headquarters moved to Geneva, Switzerland. (Details) |
| November 12 | Politics | Treaty of Rapallo between Italy and Yugoslavia. Zadar is annexed by Italy and the Free State of Fiume is established. (Details) |
| November 15 | Politics | The League of Nations holds its first general assembly. (Details) |

## Post-1920

| Dates | Campaign/Front/Theater | Events |
| 1921 |||
| October 13 | Politics | Treaty of Kars between Bolshevik Russia and Turkey. (Details) |
| 1922 |||
| February 6 | Politics | Washington Naval Treaty, limiting naval tonnage, signed by France, Italy, Japan, the United Kingdom and the United States. (Details) |
| April 10 – May 19 | Politics | Genoa Conference. Representatives of 34 countries discuss economics in the wake of the Great War. (Details) |
| April 16 | Politics | Treaty of Rapallo between Germany and Bolshevik Russia to normalize diplomatic relations. (Details) |
| September 11 | Politics | Treaty of Kars ratified in Yerevan, Armenia. (Details) |
| 1923 |||
| June 16 | Politics | The Russian Civil War ends. |
| July 24 | Politics | Treaty of Lausanne between the Allies and Turkey, successor State to the Ottoman Empire. It supersedes the Treaty of Sèvres. (Details) |
| 1924 |||
| January 27 | Politics | Treaty of Rome between Italy and Yugoslavia. Fiume is annexed by Italy and the neighbouring town of Sušak is assigned to Yugoslavia. (Details) |
| 2010 |||
| October 3 | Politics | Germany makes final reparations payments. (Details) |