1914

June 28

Assassination of Archduke Franz Ferdinand of Austria, heir to the Austro-Hungarian throne, who is killed in Sarajevo along with his wife, Duchess Sophie.

July 23

Austria-Hungary sends an ultimatum to Serbia. The Serbian response is seen as unsatisfactory.

July 28

Austria-Hungary declares war on Serbia. Russia mobilizes. The Great War begins.

July 31

Germany enjoins Russia to stop mobilizing. Russia says mobilization is against Austria-Hungary only.

August 1

Germany declares war on France and Russia.
Italy declares its neutrality.
Germany and the Ottoman Empire sign a secret alliance treaty.

August 2

Germany invades Luxembourg.

August 4

Germany invades Belgium to outflank the French army.

Britain protests the violation of Belgian neutrality, guaranteed by a treaty; German Chancellor replies that the treaty is just a chiffon de papier (a scrap of paper).

The United Kingdom declares war on Germany.

August 5

Montenegro declares war on Austria-Hungary.

The Ottoman Empire closes the Dardanelles.

August 5–August 16

The Germans besiege and then capture the fortresses of Liège, Belgium.

August 6

Austria-Hungary declares war on Russia.

Serbia declares war on Germany.

August 7

The British Expeditionary Force arrives in France.

August 9

Montenegro declares war on Germany.

August 11

France declares war on Austria-Hungary.

August 12

The United Kingdom declares war on Austria-Hungary.

August 14–August 24

Battle of the Frontiers. The Germans obtain a victory against the British Expeditionary Force and France's Fifth Army.

August 16–August 19

The Serbs defeat the Austro-Hungarians at the Battle of Cer.

August 17

The Russian army enters East Prussia. Battle of Stalluponen.

August 20

The Germans attack the Russians in East Prussia. The attack is a failure in addition to being a violation of the Schlieffen Plan.

August 17–September 2

Battle of Tannenberg: the Russian army undergoes a heavy defeat by the Germans.

August 20

The Germans occupy Brussels.

August 22

Austria-Hungary declares war on Belgium.

August 23

Japan declares war on Germany.

August 23–August 25

Battle of Kra?nik. The Austro-Hungarian First Army defeats the Russian Fourth Army.

August 24–September 7

The Germans siege and capture the Maubeuge Fortress.

August 25

Japan declares war on Austria-Hungary.

August 26

British and French forces invade Togoland, a German protectorate in West Africa.

August 26–August 27

Battle of Le Cateau. Allied retreat.

August 26–September 11

Battle of Lemberg. The Russians capture Lviv.

August 27–November 7

Battle of Tsingtao: British and Japanese forces capture the German-controlled port of Tsingtao in China.

August 28

The Royal Navy wins the First Battle of Heligoland Bight, North Sea.

August 29–August 30

Battle of Saint Quentin, aka Battle of Guise. Orderly Allied retreat.

August 30

New Zealand occupies German Samoa (later Western Samoa).

September 3–September 11

Austro-Hungarian defeat at the Battle of Rava Russka.

September 5–September 12

First Battle of the Marne. The German advance on Paris is halted, marking the failure of the Schlieffen Plan.

September 7–September 14

First Battle of the Masurian Lakes: The Russian Army of the Neman withdraws from East Prussia with heavy casualties.

September 8–September 17

Second Austro-Hungarian attempt at invading Serbia fails.

September 9

Theobald von Bethmann Hollweg lays out Germany's war aims.

September 11–September 21

Australian forces occupy German New Guinea.

September 13

Troops from South Africa begin invading German South-West Africa.

September 13–September 28

The First Battle of the Aisne ends in a substantial draw. The Race to the Sea begins.

September 14

Erich von Falkenhayn replaces Helmuth von Moltke the Younger as German Chief of Staff.

September 17

The Siege of Przemy?l begins

September 28–October 10

The Germans siege and capture Antwerp, Belgium.

September 29–October 31

Battle of the Vistula, aka Battle of Warsaw.

October 16–October 31

Battle of the Yser. French and Belgian forces secure the coastline of Belgium.

October 19–November 22

The First Battle of Ypres ends the Race to the Sea. The Germans are prevented from reaching Calais and Dunkirk.

November 1

Russia declares war on the Ottoman Empire.
Battle of Coronel. Von Spee's German cruiser squadron defeats a Royal Navy squadron under Christopher Cradock.

November 2

The United Kingdom begins the naval blockade of Germany.

November 3

Montenegro declares war on the Ottoman Empire.

November 3–November 5

Von Lettow-Vorbeck's German colonial forces defeat the British at the Battle of Tanga, German East Africa.

November 5

France and the United Kingdom declare war on the Ottoman Empire.

November 6

The Austro-Hungarians enter Belgrade.

November 9

Battle of Cocos, northeast Indian Ocean. The Australian cruiser Sydney destroys the German cruiser Emden.

November 11–December 6

Battle of Lodz

November 11

Sultan Mehmed V declares Jihad on the Allies.

December 8

Battle of the Falklands. Von Spee's German cruiser squadron is defeated by the Royal Navy.

December 16

The German fleet shells Scarborough and Hartlepool, England.

December 24-December 25

An unofficial Christmas truce is declared between large numbers of German and French forces.

December 29–January 2, 1915

The Russians win the Battle of Sarikamis, Caucasia.

1915

January 2

The Russian offensive in the Carpathians begins. It will continue until April 12.

January 19

First Zeppelin raid on Great Britain.

January 24

Battle of Dogger Bank between squadrons of the British Grand Fleet and the German Hochseeflotte.

January 28–February 3

The Ottomans fail to capture the Suez Canal.

January 31

Battle of Bolimov. First German use of Chemical weapons.

February 4

Germany begins submarine warfare against merchant vessels.

February 7–February 22

Second Battle of the Masurian Lakes. The Russian X Army is defeated.

February 19

British and French naval attack on the Dardanelles. The Gallipoli Campaign begins.

March 10–March 13

Battle of Neuve Chapelle. After an initial success, a British offensive is halted.

March 22

The Siege of Przemy?l ends. The Russians capture the fortress.

April 22–May 25

At the Second Battle of Ypres, ending in a stalemate.

April 25

Allied forces land on Gallipoli.
London Pact between the Entente and Italy.

April 28

First Battle of Krithia. The Allied advance is repelled.

May 1–May 3

Battle of Gorlice-Tarnów: the German troops under General Mackensen break through the Russian lines in Galicia.

May 6–May 8

Second Battle of Krithia. The Allied attempts at advancing are thwarted again.

May 7

The British liner Lusitania is sunk by a German U-boat.

May 10

Troops from Hungary rout the Russians at Jaros?aw. Lviv is again in Austrian hands.

May 12

Windhoek, capital of German South-West Africa, is occupied by South African troops.

May 23

Italy declares war on Austria-Hungary.

June 4

Third Battle of Krithia. Yet another Allied failure.
The Russians leave Przemysl.

June 22

Mackensen breaks again through the Russian lines in the Lviv area.

June 23–July 7

First Battle of the Isonzo.

June 27

The Austro-Hungarians re-enter Lviv.

June 28–July 5

The British win the Battle of Gully Ravine.

July 9

The German forces in South-West Africa surrender.

July 18–August 3

Second Battle of the Isonzo.

August 5

The Germans occupy Warsaw.

August 6–August 29

Battle of Sari Bair, aka the August Offensive. Last and unsuccessful attempt by the British to seize the Gallipoli peninsula.

September 1

Germany suspends unrestricted submarine warfare.

September 8

Nicholas II removes Grand Duke Nicholas Nikolayevich as Commander-in-Chief of the Russian Army, personally taking that position.

September 19

The Germans occupy Vilnius. The Gorlice-Tarnów Offensive ends.

September 25–September 28

Battle of Loos. A major British offensive fails.

October 6

Serbia is invaded by Germany, Austria-Hungary and Bulgaria.

October 14

Bulgaria declares war on Serbia

October 15

The United Kingdom declares war on Bulgaria.

October 16

France declares war on Bulgaria.

October 18–November 4

Third Battle of the Isonzo

October 19

Italy and Russia declare war on Bulgaria.

October 27

A French army lands in Salonika and, with the help of British and Italian troops, sets up a Balkan Front.

November 10–December 2

Fourth Battle of the Isonzo

November 22–November 25

Battle of Ctesiphon, in present-day Iraq.

November 27

The Serbian army collapses. It will retreat to the Adriatic Sea and be evacuated by the Italian and French Navies.

December 7

The Siege of Kut, Mesopotamia, by the Ottomans begins.

December 19

Douglas Haig replaces John French as commander of the British Expeditionary Force.

1916

January 8–January 16

Austro-Hungarian offensive against Montenegro, which capitulates.

January 9

The Gallipoli Campaign ends in an Allied defeat and an Ottoman victory.

January 11

Corfu occupied by the Allies.

January 24

Reinhard Scheer is appointed commander of Germany's Hochseeflotte.

January 27

Conscription introduced in the United Kingdom by the Military Service Act.

February 13–February 16

Battle of Erzurum.

February 21

The Battle of Verdun begins.

February 28

German Kamerun (Cameroon) surrenders.

March 1

Germany resumes unrestricted submarine warfare.

March 1–March 15

Fifth Battle of the Isonzo.

March 8

Battle of Dujaila: a British attempt to relieve Kut fails.

March 18–April

Lake Naroch Offensive.

April 23

Easter Rising by Irish rebels against the United Kingdom.

April 29

The British forces under siege at Kut surrender to the Ottomans.

May 10

Germany suspends unrestricted submarine warfare.

May 15–June 10

Austro-Hungarian Strafexpedition in Trentino.

May 31–June 1

Battle of Jutland between Britain's Grand Fleet and Germany's Hochseeflotte.

June 4

The Brusilov Offensive begins.

June 5

The Arab Revolt in Hejaz begins.
The HMS Hampshire is sunk off the Orkney Islands; Lord Kitchener dies.

June 10

Italy: Paolo Boselli succeeds Antonio Salandra as Prime Minister.

July 1

The Battle of the Somme begins.

July 2

Battle of Erzincan.

July 14

Battles for Longueval and Delville Wood (Initial phase of the Battle of the Somme)
Battle of Bazentin Ridge (Initial phase of the Battle of the Somme)

July 23–August 7

Battle of Pozieres (Initial phase of the Battle of the Somme)

August 3–August 5

Battle of Romani. Ottoman attack on the British in the Sinai peninsula fails.

August 3–August 17

Sixth Battle of the Isonzo. The Italians capture Gorizia (August 9).

August 18–September 5

Battle of Guillemont (intermediate phase of the Battle of the Somme)

August 27

Italy declares war on Germany.
Romania enters the war on the Entente's side. Her army is defeated in a few weeks.

August 29

Paul von Hindenburg replaces Erich von Falkenhayn as German Chief of Staff.

September 6

The Central Powers create a unified command.

September 9

Battle of Ginchy (intermediate phase of the Battle of the Somme)

September 10–November 19

Allied offensive on the Salonika Front.

September 14–September 17

Seventh Battle of the Isonzo

September 15

Battle of Flers-Courcelette (last offensive of the Battle of the Somme). The British use armored tanks for the first time in history.

September 20

The Brusilov Offensive ends with a substantial Russian success.

September 25

Battle of Morval (part of the final stages of the Battle of the Somme)

September 26–September 28

Battle of Thiepval Ridge (part of the final stages of the Battle of the Somme)

October 1–November 5

Battle of Le Transloy (part of the final stages of the Battle of the Somme)

October 9–October 12

Eighth Battle of the Isonzo.

October 24

The French recapture Fort Douaumont near Verdun.

November 1–November 4

Ninth Battle of the Isonzo.

November 13–November 15

Battle of the Ancre (closing phase of the Battle of the Somme)

November 18

The Battle of the Somme ends with enormous casualties and no winner.

November 21

HMHS Britannic sinks after hitting a German mine
Francis Joseph I, Emperor of Austria and King of Hungary, dies and is succeeded by Charles I.

November 25

David Beatty replaces John Jellicoe as commander of the Grand Fleet. Jellicoe becomes First Lord of the Sea.

December 5–December 7

United Kingdom: Prime Minister Henry Asquith resigns and is succeeded by David Lloyd George.

December 6

The Germans occupy Bucharest. The capital of Romania moved to Ia?i.

December 13

Robert Nivelle replaces Joseph Joffre as Commander-in-Chief of the French Army.

December 23

Battle of Magdhaba in the Sinai peninsula.

December 27

Togoland is divided into British and French administrative zones.

December 29

Grigori Rasputin, Russia's éminence grise, is assassinated.

1917

January 9

Battle of Roof. The British drive the Ottomans out of Sinai.

January 16

The German Foreign Secretary Arthur Zimmermann sends a telegram to his ambassador in Mexico, instructing him to propose the Mexican government an alliance against the United States.

February 1

Germany resumes unrestricted submarine warfare.

February 23

Second Battle of Kut. The British recapture the city.

February 23–April 5

The Germans withdraw to the Hindenburg Line.

March 1

Arz von Straussenberg replaces Conrad von Hötzendorf as Austro-Hungarian Chief of Staff.

March 8–March 11

The British capture Baghdad.

March 15

Russia: Czar Nicholas II abdicates. A provisional government is appointed.

March 26

First Battle of Gaza. The British attempt to capture the city fails.

April 6

The United States of America declares war on Germany.

April 9–April 12

The Canadians obtain a significant victory in the Battle of Vimy Ridge.

April 16–May 9

The Second Battle of the Aisne (aka Nivelle Offensive) ends in disaster for both the French army and its commander Robert Nivelle.

April 19

Second Battle of Gaza. The Ottoman lines resist a British attack.

April 29–May 20

Series of mutinies in the French army.

May 5–May 15

Allied offensive on the Salonika Front.

April 9–May 16

Battle of Arras. The British attack a heavily fortified German line without obtaining any strategic breakthrough.

May 12–June 6

Tenth Battle of the Isonzo.

May 15

Philippe Petain replaces Robert Nivelle as Commander-in-Chief of the French Army.

May 23

Battle of Mount Hermada in the Karst.

June 7–June 8

The British recapture Messines Ridge.

June 10–June 29

Battle of Mount Ortigara.

June 12

Greece: King Constantine I abdicates.

June 25

First American troops land in France.

July 1–July 19

The Kerensky Offensive fails. It is the last Russian initiative in the war.

July 6

Arab rebels led by Lawrence of Arabia seize the Jordanian port of Aqaba.

July 20

Corfu Declaration about the future Kingdom of Yugoslavia.

July 31

The Battle of Passchendaele (aka Third Battle of Ypres) begins.

August 6–August 20

Battle of Marasesti.

August 18–August 28

Eleventh Battle of the Isonzo.

September 8

Russia: General Kornilov's coup attempt fails.

September 27–September 28

Battle of Ramadi, Mesopotamia.

October 24–November 4

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.

October 30

Italy: Vittorio Emanuele Orlando succeeds Paolo Boselli as Prime Minister.

October 31–November 7

Third Battle of Gaza. The British break through the Ottoman lines.

November 2

Balfour Declaration: the British government supports plans for a Jewish "national home" in Palestine.

November 5

The Allies agree to establish a Supreme War Council at Versailles.

November 7

The October Revolution begins in Russia. The Bolsheviks seize power.

November 8

Armando Diaz replaces Luigi Cadorna as Commander-in-Chief of the Italian Army.

November 9–December 28

First Battle of the Piave: the Austro-Hungarians and Germans try unsuccessfully to cross the river.

November 10

The Battle of Passchendaele (aka Third Battle of Ypres) ends in a stalemate.

November 13

France: Paul Painlevé is replaced by Georges Clemenceau as Prime Minister.

November 17

Second Battle of Heligoland Bight, North Sea.

November 20–December 3

Battle of Cambrai. A British attack fails and the battle results in a stalemate.

December 7

The United States declares war on Austria-Hungary.

December 8–December 26

Battle of Jerusalem. The British enter the city (December 11)

December 23

Russia signs an armistice with Germany.

1918

January 8

Woodrow Wilson outlines his Fourteen Points.

February 18

Fighting resumes on the Eastern Front.

February 21

The British capture Jericho.

February 25

German troops capture Estonia.

March 3

At Brest-Litovsk, Leon Trotsky signs the peace treaty with Germany.

March 21–March 25

First phase of the Spring Offensive (Operation Michael). The Germans obtain a Pyrrhic victory.

March 23–August 7

Artillery bombardment of Paris.

March 26

French Marshall Ferdinand Foch is appointed Supreme Commander of all Allied forces.

April 1

Royal Air Force founded by combining the Royal Flying Corps and the Royal Naval Air Service.

April 4

Second phase of the Spring Offensive (Operation Georgette). The results are disappointing for the Germans.

May 7

Treaty of Bucharest between Romania and the Central Powers. It will never be ratified.

May 27–June 6

Third Battle of the Aisne (aka Operation Blücher-Yorck, third phase of the Spring Offensive). After initial gains, the German advance is halted.

June 9–June 12

Final phase of the Spring Offensive (Operation Gneiseau). Despite substantial territorial gains, the Germans do not achieve their strategic goals

June 13–June 23

Second Battle of the Piave: the Austro-Hungarian offensive is repelled.

July 15–August 5

Second Battle of the Marne and last German offensive on the Western Front, which fails when the Germans are counterattacked by the French.

August 8–August 11

Battle of Amiens, first phase of the Hundred Days Offensive.

September 12

Battle of Havrincourt, a phase of the Hundred Days Offensive.

September 15

The Allies break through the Bulgarian lines at Dobro Polje.

September 18–September 19

Battle of Doiran, The Bulgarians halt the British and Greek advance.

September 18–October 10

Battle of the Hindenburg Line, a phase of the Hundred Days Offensive. The Allies break through the German lines.

September 19–September 21

Battle of Megiddo. The British conquer Palestine.

September 26–November 11

Meuse-Argonne Offensive, the final phase of the Hundred Days Offensive and of World War I.

September 30

Bulgaria signs an armistice with the Allies.

October 1

The British enter Damascus.

October 20

Germany suspends submarine warfare.

October 24–November 4

Battle of Vittorio Veneto. The Austro-Hungarian army is routed. The Italians enter Trent and land at Triest.

October 29

Wilhelm Groener replaces Erich Ludendorff as Hindenburg's deputy.

October 29

Germany's Hochseeflotte mutinies.

October 30

The Ottoman Empire signs the Armistice of Mudros.

November 3

Austria-Hungary signs the armistice with Italy, effective November 4.

November 9

Germany: Kaiser William II abdicates; republic proclaimed.

November 10

Austria-Hungary: Kaiser Charles I abdicates.

November 11

At 6 am, Germany signs the Armistice of Compiègne. End of fighting at 11 a.m.

November 12

Austria proclaimed a republic.

November 14

Czechoslovakia proclaimed a republic.
German U-boats interned.
3 days after the armistice, fighting ends in the East African theater when General von Lettow-Vorbeck agrees a cease-fire on hearing of Germany's surrender.

November 21

Germany's Hochseeflotte surrendered to the United Kingdom.

November 22

The Germans evacuate Luxembourg.

November 23

9 days after agreeing a cease-fire, General von Lettow-Vorbeck formally surrenders his undefeated army at Abercorn in present-day Zambia.

November 27

The Germans evacuate Belgium.

December 4

Yugoslav independence proclaimed.

1919

January 18

Treaty of Versailles between the Allies and Germany: the Peace Conference opens in Paris.

January 25

Proposal to create the League of Nations accepted.

June 21

German High Seas Fleet (53 ships) scuttled in Scapa Flow with nine deaths, the last casualties of the war.

June 28

Treaty of Versailles signed.

July 8

Germany ratifies the Treaty of Versailles.

July 21

The United Kingdom ratifies the Treaty of Versailles.

1920

January 10

First meeting of the League of Nations held in London. Official end of World War I.
Free City of Danzig established.

January 21

The Paris Peace Conference ends.

February 10

A plebiscite returns Northern Schleswig to Denmark.

April 19–April 26

Conference of Sanremo, Italy, about League of Nations mandates in former Ottoman territories of the Middle East.

June 4

Treaty of Trianon between the Allies and Hungary.

August 10

Treaty of Sèvres between the Allies and the Ottoman Empire. The treaty is not recognized by the Turkish national movement, which consider the Istanbul government illegitimate.

September 8

Gabriele D'Annunzio proclaims in Fiume the Italian Regency of Carnaro.

November 1

League of Nations headquarters moved to Geneva, Switzerland.

November 12

Treaty of Rapallo between Italy and Yugoslavia. Zadar is annexed by Italy and the Free State of Fiume is established.

November 15

The League of Nations holds its first general assembly.

Post-1920

1921

October 13

Treaty of Kars between Bolshevik Russia and Turkey.

1922

February 6

Washington Naval Treaty, limiting naval tonnage, signed by France, Italy, Japan, the United Kingdom and the United States.

April 10–May 19

Genoa Conference. Representatives of 34 countries discuss economics in the wake of the Great War.

April 16

Treaty of Rapallo between Germany and Bolshevik Russia to normalize diplomatic relations.

September 11

Treaty of Kars ratified in Yerevan, Armenia.

1923

July 24

Treaty of Lausanne between the Allies and

Turkey, successor State to the Ottoman Empire. It supersedes the Treaty of Sèvres.

1924

January 27

Treaty of Rome between Italy and Yugoslavia. Fiume is annexed by Italy and the neighboring town of Susak is assigned to Yugoslavia.

Source: WikiPedia