The telegram is intercepted by British naval intelligence.
German Foreign Secretary, Arthur Zimmerman, sends a secret telegram to the German minister in Mexico telling him to offer German support to the Mexicans if they were to attack the United States
Nancy Astor becomes the first woman to take up her seat as an MP in the House of Commons
To support French operations in Artois, British troops attack in French Flanders but achieve no real gains. Battle continues until 10 May.
Colonel Paul von Lettow-Vorbeck ends his long campaign in German East Africa and surrenders undefeated
Germany promises to support Austria-Hungary in its confrontation with Serbia over the assassination
Serbian troops forced to retreat through Albania to the Adriatic coast.
Serbia defeated by combined armies of Austria-Hungary and Bulgaria
Bolshevik demonstrations begin in Germany
German armies in East Prussia defeat Russian forces. Battle lasts until 30 August.
Third Military Service Act passed by the British parliament increasing eligibility for armed service to those aged up to 51 and men living in Ireland
German armies in East Prussia defeat Russian forces. Battle lasts until 15 September.
Continues to 16 October when the lines reach the Belgian coast.
Known as the 'Race to the Sea', the German, French and British armies move north from the Aisne and try to outflank each other
French forces, with British support, stop the German advance through northern France only a short distance from Paris and launch a counter-attack. Battle continues until 10 September.
Britain, France, Russia, Japan and Italy jointly renew the Pact of London
Victory parade held in London. Temporary Cenotaph built to represent the dead.
British troops stationed in the Punjab in northern India kill 379 civilians and wound 1,200 more at Amritsar during protests calling for self-government in India
General Robert Nivelle replaced in command of the French armies by General Phillipe Pétain
Immediate calls follow for a second hundred thousand.
100,000 British men already recruited by Kitchener
British government approves the creation of a National War Museum in London (changed to the Imperial War Museum in December, to reflect the efforts of people from across the Empire)
European war becomes global when Japan declares war on Germany
On the Somme, the British launch a dawn attack that captures the villages of Bazentin and Longueval. British and Indian cavalry make a short-lived charge towards High Wood.
Austria-Hungary issues ultimatum to Serbia to accept its terms or face recrimination
Largest and final German aeroplane raid on London, involving 33 aircraft
British forces take Dar es Salaam in German East Africa
Following their advance through the former Allied lines, the Germans use a long range railway gun to shell Paris
Germans launch strong counter-attacks at Cambrai and recapture almost all the ground they had lost
Belgium refuses Germany permission to cross its territory to reach France and asserts its neutrality under international treaty
Increasing numbers of women start to be employed in British munitions factories
Over 1 million refugees flee the country over the coming weeks, mostly to the Netherlands but also to France and Britain.
Germany declares war on Belgium and invades the country
First contingent of US troops arrives in France
Advocates a 'return to normalcy' following the the war, leading the USA to a position of isolationism.
Warren Harding elected as the 29th President of the United States in a landslide victory
Italians launch a strong offensive in the north-east along the River Piave, against the Austro-Hungarian line which begins to collapse.
Royal Navy ships launch a raid against Zeebrugge and Ostend, aimed at blocking the exits from the inland German submarine bases
First German aircraft raid on British south coast towns
Austro-Hungarian forces begin their first invasion of Serbia
British and Canadian troops begin the final assault on the village.
39 German submarines surrender at Harwich.
Elements of the German High Seas Fleet surrender off Rosyth
American President Woodrow Wilson announces '14 Points' that he believes could form the basis for a peace agreement
Conscription begins in Britain when the Military Service Act comes into effect
First daylight aeroplane raid on Britain by German Gotha bombers
Allied troops begin attacks on the outer defences of the strong German Hindenburg Line in France.
Allied troops successfully break through the Hindenburg Line. Fighting continues until 2 October.
Germany begins a policy of unrestricted submarine warfare
Austro-Hungarians launch an attack against Italian troops on the Asiago front in the Italian alpine region of Trentino, advancing up to 19 km(12 miles)
Daylight Gotha bomber raid on London kills 57 people
At Verdun, only 5km (three miles) from the city, the Germans suspend their attacks in order to move troops to the Somme
Treaty of Saint-Germain signed between the Allies and Austria
Ships will be sunk without warning, including neutral vessels. Continues until September.
Germany announces its first sustained U-boat (submarine) campaign against merchant and passenger ships approaching Britain
Three British cruisers, HMS Aboukir, Hogue and Cressy sunk by a German submarine off the German coast
Bolsheviks, led by Lenin and Trotsky, seize power and overthrow the Provisional Government
British ships blockading the Dardanelles bombard the Turkish forts guarding the entrance to the Straits
Encounter between British and German battlecruisers in the North Sea.
General Joseph Joffre replaced in command of the French armies by General Robert Nivelle
Newly formed Soviet Red Army goes into action against the Germans for the first time
Kut al Amara recaptured as part of a new British offensive in Mesopotamia aimed at reaching Baghdad
USA breaks off diplomatic relations with Germany as a result of the resumed submarine campaign
British forces from Egypt led by General Sir Archibald Murray nearly break through Turkish lines in Palestine but fail to exploit their success.
German troops occupy Brussels, the Belgian capital
Lenin arrives back in Russia by a sealed train allowed to pass through Germany from Switzerland
In France, General Erich von Falkenhayn is replaced as Chief of the General Staff of the German field armies by Field Marshal Paul von Hindenburg, with General Erich Ludendorff as Chief Quartermaster General
At a conference in Doullens, French General Ferdinand Foch becomes General in Chief of all the Allied armies in France
Turkish forces cross the Sinai Desert and assault the Suez Canal
Together they form the focus for British national commemoration of the dead of the First World War.
At a memorial service in London the permanent Cenotaph is unveiled in Whitehall, and the Unknown Warrior buried in Westminster Abbey
Mutiny in the German High Seas Fleet at Wilhelmshaven
They suffer a series of defeats and setbacks. Fighting continues until 18 July.
Russians begin a summer offensive against the Germans directed by Alexander Kerensky, war minister in the Provisional Government
Meat rationing introduced across Britain
Intense fighting as the French attempt to advance into Germany. French driven back after suffering severe losses. Continues until 25 August.
In the South Atlantic, a reinforced British naval squadron defeats the German East Asiatic Squadron.
Belgrade captured by the Austro-Hungarians
German forces take the Belgian city of Antwerp
Treaty of Trianon signed with the Hungarians
Austria-Hungary launches its third invasion of Serbia
Rumania enters the war on the Allied side but is quickly defeated by Germany, Austria-Hungary and Bulgaria
Herbert Asquith replaced as British Prime Minister by David Lloyd George, who takes over leadership of the wartime coalition
The Bolshevik Russian government signs a peace treaty with the Germans and other Central Powers at Brest-Litovsk
The London Scottish become the first battalion of British Territorial troops to go into battle at Messines in Belgium
General Sir Douglas Haig replaces Field Marshal Sir John French as Commander in Chief of the British Expeditionary Force in France and Belgium
French and American troops begin a steady push against the Germans along the southern part of the front. Fighting continues until 15 October.
Greek landings in Smyrna (Izmir) develop into a Graeco-Turkish War with increasingly bitter fighting between Turkish and Greek forces
German forces facing the Somme withdraw around 40km (25 miles) to new, strongly prepared defences known to the British as the Hindenburg Line
British, French, Australian and New Zealand troops land on and around the Gallipoli peninsula in support of the naval attack on the Dardanelles. Fighting continues until January 1916.
The fighting at Loos carries on until 4 November.
Co-ordinated Allied offensive in France, with French attacks in the Second Battle of Champagne and Third Battle of Artois, and British attacks at the Battle of Loos
British forces advance over 5km (3½ miles) on the opening day. The Canadians seize Vimy Ridge. Fighting continues until 4 May with increasingly heavy casualties.
David Lloyd George, the former Chancellor of the Exchequer, appointed Minister of Munitions to increase the production of weapons and ammunition.
Coalition government formed by the British Prime Minister Herbert Asquith as tensions rise over his handling of the war
Third Battle of Ypres begins, popularly known as Passchendaele
Whitehaven in Cumberland, on Britain's west coast, shelled by a German U-boat
General Helmuth von Moltke replaced in command of the German armies in France and Belgium by General Erich von Falkenhayn
In Mesopotamia, Turkish forces stop the Anglo-Indian advance on Baghdad only 40 km (25 miles) south of the city.
Treaty of Versailles signed between the Allied and Associated governments and Germany
Theobald von Bethmann-Hollweg replaced as German Chancellor by Georg Michaelis
Russian troops initially pushed back by the Turks before the situation is reversed. Battle continues until 2 January 1915.
German Chancellor, Theobald von Bethmann-Hollweg, sends a peace note to the Allies offering to open talks in a neutral country
Mannock was posthumously awarded the Victoria Cross.
Major Edward Mannock, Britain's highest rated 'air ace', shot down and killed
Rationing begins in London and the south of Britain
The Germans launch a second offensive (Operation Georgette) against the British line in Flanders, again capturing much ground. Fighting continues until 29 April.
The ships of the German High Seas, interned at Scapa Flow in the Orkney Islands, are sunk by their own crews
British Cabinet decide to keep the Cenotaph at its location in Whitehall and replace it with a permanent structure
Principle of League of Nations agreed at Peace conference
Socialist unrest in Germany, known as the Spartacist Revolt
British troops in Palestine are heavily defeated by Turkish forces in a renewed attempt to break through.
Germans capture Riga on the Baltic coast using their new 'stormtrooper' tactics
German and Austro-Hungarian forces capture the fortress of Brest-Litovsk in Russian Poland
An Indian Army force leaves Bombay to secure British interests in the Persian Gulf by landing in Mesopotamia, part of the Ottoman Empire (Turkey)
No-Conscription Fellowship holds its first national meeting in London to resist forcible conscription into the army and support conscientious objectors
Second Military Service Act passed by the British parliament, extending conscription to married men
With British and French troops transferred from the Western Front, the Italians manage to establish a new front along the River Piave.
British squadron of ships defeated by German East Asiatic Squadron.
Battle of Coronel off the coast of Chile
US Senate rejects the Treaty of Versailles and membership of the League of Nations
Australian and British troops suffer heavy casualties in an attack on the German line in French Flanders.
First Military Service Act passed by the British parliament making all single men between 18 and 41 eligible for conscription into the army
Japan sends Germany an ultimatum demanding the evacuation of its naval base at Tsingtau in China
Germany invades Luxembourg and demands permission to move through neutral Belgium against France
British forces enter the German protectorate of Togoland in West Africa
Batum, in the Caucasus, captured by Turkish troops who take advantage of Russia's withdrawal from the war to recapture lost ground
Led by General Alexei Brusilov, a major Russian offensive is launched in western Ukraine, principally against the Austro-Hungarians, who are forced into steady retreat
Offensive launched by the French under General Robert Nivelle along the Chemin des Dames. Following heavy casualties, fighting called off on 20 April after few gains.
British Secretary of State for War, Field Marshal Lord Kitchener, drowned en route to Russia when HMS Hampshire strikes a mine off the Orkney Islands and sinks
Austro-Hungarians launch a renewed attack on the Italian line in the north-east along the River Piave. The attack is beaten off. Fighting continues to 24 June.
German airships raid Britain for the first time, attacking Great Yarmouth and King's Lynn
Austria-Hungary begins mobilization of its army, including along the Russian border
British parliament gives approval for the recruitment of half a million men to begin a rapid expansion of the British Army
First meeting of the League of Nations at its permanant headquarters in Geneva
At Gallipoli, Australian and New Zealand troops fight off a very heavy Turkish attack. After weeks of effort on both sides, it is clear stalemate has been reached.
The aim is for the ships to force their way through the Dardanelles and capture the Turkish capital, Constantinople (present day Istanbul).
Royal Navy ships begin shelling the forts guarding the entrance to the Dardanelles in Turkey
Allied peace terms are handed to the Austrians
Italian troops in the north-east advance and capture Gorizia, one of the few significant advances on the Isonzo front. Fighting continues until 17 August.
London stock market closes due to European crisis
One of the French air force's leading fighter aces, Captain Georges Guynemer, shot down and killed in Belgium
French launch a new attack at Verdun and recapture more ground lost the previous year
Able to fire directly forward by shooting through the propellor arc, the Fokker establishes German air superiority until Spring 1916.
German Fokker aircraft deployed in numbers along the Western Front
As Austria-Hungary's ally, Germany demands an end to Russian mobilization
Woodrow Wilson re-elected President of the United States of America
French launch attack for limited gains. Battle lasts until 18 June.
Three ships are sunk; three are badly damaged. Naval operations are suspended.
British and French warships at the Dardanelles try to force their way through the Narrows
The German Kaiser, Wilhelm II, abdicates and prepares to leave Germany
Representation of the People Act receives Royal Assent, extending the right to vote to almost all British men as well as women aged over 30
Canadian troops in Belgium recapture Mons
Russian civil war ends when White Russian forces are crushed by the Red Army of the Bolshevik government
French troops try to block the German advance north-west of the Ardennes.
In the Caucasus, Russian forces push back the Turks and go on to capture Erzerum and Trabzon
British government issues the Balfour Declaration, supporting the establishment of a Jewish homeland in Palestine
British government announces its policy of building new 'Homes Fit for Heroes'
Imperial War Museum opened at Crystal Palace in London by King George V
Germans recommence submarine attacks against merchant and passenger vessels approaching Britain
First units of Kitchener's New Armies, forming the 9th (Scottish) Division, leave Britain for overseas service
Italy declares war on Austria-Hungary and moves to secure strategically important points along their shared border
Russians capture the Austro-Hungarian city of Przemysl
British and French troops land in the Greek city of Salonika to support Serbia, by threatening the southern flank of Bulgaria
Alexander Kerensky becomes Prime Minister of Russia
Austro-Hungarian forces recapture the city of Lemberg (Lvov) from the Russians
Austro-Hungarian government seeks an armistice with the Italians
Fighting ends in France and Belgium at 11.00am.
Germany signs an armistice with the Allies, agreeing to an immediate cease fire and the withdrawal of its troops to its own borders
British, Australian, Canadian and French forces launch a powerful strike against the German army on the Somme. General Ludendorf calls it 'the black day of the German army'. Fighting now continues until 11 November.
Austro-Hungarians and Germans break through the Italian lines on the Isonzo and force a retreat of 140km (90 miles). 300,000 Italian prisoners are taken. Fighting carries on until 10 November.
Troops evacuated from the Suvla and Anzac beachheads at Gallipoli
British and Indian troops undertake their first offensive in France with limited success.
US Congress passes a bill to recruit half a million men for war service
First Australian and New Zealand troops leave Australia, expecting to continue their training in Britain
British royal family changes its name from Saxe-Coburg-Gotha to Windsor
Germany declares war on Russia and begins mobilization
Indian Army troops land in Mesopotamia to protect British oil interests in neighbouring Persia, and encourage an Arab revolt against Turkish rule
First troops leave Canada and Newfoundland to continue their training in Britain
German mine layer Königen Luise becomes the first naval casualty of the war when sunk in the North Sea by three British ships
Allied troops renew their offensive in France, beginning a series of battles that force the Germans steadily back.
In difficult conditions, the Russians initially do badly but soon recover. Fighting continues until 18 January 1915.
Turkish forces launch attacks on the Russians in the Caucasus
British troops undertake another attack in French Flanders only a short distance from Aubers Ridge. Battle carries on until 25 May.
Austria-Hungary blames Serbia for supporting this terrorist attack in Bosnia-Herzegovina.
Archduke Franz Ferdinand, heir to the Austro-Hungarian throne, assassinated in Sarajevo by Gavrilo Princip
In self-defence and in support of Serbia, Russia orders partial mobilization of its army
Following a heavy bombardment, Germans launch major attack against the French intending to cause heavy casualties. Fighting continues until 18 December.
Britain and France declare war on Austria-Hungary
Italians launch disappointing attack on the Austro-Hungarians on the Trentino front in the Alps. Continues until 29 June.
French and Serbian troops at Salonika launch strong offensive against the Bulgarians and make steady gains
Italian troops attack Austro-Hungarians in north-eastern Italy, aiming to reach Trieste. Disappointing results but operations continue until 7 July.
Second in a series of eleven battles launched along the Isonzo river in north-eastern Italy. Fighting on the Isonzo continues until October 1917.
Bolshevik government in Russia signs an armistice with the Germans, suspending hostilities on the Eastern Front
The Provisional Government assumes power.
Tsar Nicholas II abdicates as ruler of Russia
Jerusalem taken by the British forces in Palestine, ending 673 years of Turkish rule
Last troops evacuated from the Helles beachhead at Gallipoli
Russian forces capture the fourth largest city in Austria-Hungary. Battle lasts until 11 September.
Japanese troops, with British support, capture the German naval base of Tsingtau
The Zimmerman telegram offering German support to a Mexican attack on the US is made public in US newspapers, with the approval of President Wilson
Former Tsar Nicholas II and his family executed by the Bolsheviks
The first action of a long-running campaign in East Africa. German forces led by Colonel Paul von Lettow-Vorbeck defeat British and Indian troops. Fighting continues until 5 November. The campaign lasts until November 1918.
German government seeks an armistice based on President Wilson's 14 Points
Capture of Belgrade, the Serbian capital, by the Austro-Hungarians
Imperial War Graves Commission formally established in London (becoming the present Commonwealth War Graves Commission in 1960)
General Sir Edmund Allenby takes over command of the Egyptian Expeditionary Force from General Sir Archibald Murray
Outbreak of mutinies in French army units at Châlons-sur-Marne following their recent heavy casualties and defeat
To combat the German submarine threat, British introduce the convoy system, moving large numbers of merchant ships together under naval protection.
First British aeroplane raid on Germany against Dusseldorf and Cologne airship sheds
Third German offensive (Operation Blucher) against the French line, centres on the Chemin des Dames above the River Aisne. Fighting continues to 6 June.
British Expeditionary Force (BEF), under the command of Field Marshal Sir John French, begins to land in France
Fort Vaux recaptured by the French at Verdun
First council meeting of League of Nations held in Paris
Anglo-Indian garrison finally surrenders to the besieging Turkish forces after 143 days.
Nationwide release follows a week later. The film is the first documentary to show actual footage of men fighting in battle. It is seen by more than 20 million people.
The Battle of the Somme documentary film released for viewing in 34 cinemas in London
Turkish warships shell Russian coastal towns in the Black Sea.
Turkey joins the war on the side of Germany and Austria-Hungary
Third Battle of Ypres ends with the capture of Passchendaele village
Led by Allenby, British troops, combined with an Australian attack at Beersheba, finally breaking through Turkish lines in Palestine
Naval action between British and German ships off the Heligoland Bight in the North Sea
At Salonika, Allied forces liberate the Serbian town of Monastir after an offensive lasting two months
Fort Douamont is recaptured by the French. Fighting continues until 18 December.
Major French counter-attack at Verdun under General Robert Nivelle pushes the Germans back
Fighting begins between French and German troops along the border linking the two countries. Continues until early September with heavy casualties.
In East Prussia, Germans defeat the Russians who begin to retreat. Battle continues until 22 February.
Fifth major German attack since March. On a smaller scale, German troops assault the French line facing the River Marne. For the first time the German attack is unsuccessful. Continues to 18 July.
In Belgium, Allies make a strong advance from Ypres that begins to push the Germans back. Fighting continues until 10 October.
Last German forces in the Cameroons surrender to British
The first 'call to arms' issued by the British Secretary of State for War, Field Marshal Lord Kitchener
Germans launch major assault on French, British and Canadian troops around Ypres and use poison gas extensively for the first time. Fighting continues until 27 May.
German Gotha bombers start night raids on London
An Arab force from the Hejaz guided by T E Lawrence captures the Red Sea port of Aqaba
Allied terms for a peace treaty are handed to the German government
German and Austro-Hungarian armies defeat the Russians in the centre of their line and begin to drive them back. After weeks of retreat, the Russians lose most of their territory in Poland.
Britain promises to defend Belgian neutrality
British Grand Fleet confronts the German High Seas Fleet in the North Sea, off the coast of Denmark. Although the British lose more ships, the German fleet is driven back to port and remains there for the rest of the war.
Royal Navy warships begin a concerted blockade of Germany and its ports
shooting of Miss Cavell
In Brussels the Germans execute the British nurse, Edith Cavell, for espionage and aiding escaped prisoners
French and British troops stand firm around the Belgian city of Ypres, preventing the German armies breaking through to the Channel ports. Continues to 22 November.
Treaty of Neuilly is signed with the Bulgarians
First German airship shot down over Britain, to the north of London
After all attempts to move inland have been defeated, a new British landing is made at Suvla Bay, linked to an assault on the hills beyond the Australian and New Zealand position. The operations fail.
Troops of the Australian and New Zealand Army Corps (ANZAC) disembark in Egypt to complete their training after it is decided conditions in Britain are unsuitable
Treaty of Sévres signed between the Allies and Turkey
Bulgaria agrees an armistice with the Allies
Pope Benedict XV makes another appeal for peace
David Lloyd George appointed Secretary of State for War in place of the late Lord Kitchener
The Royal Air Force is formed by combining the army's Royal Flying Corps with the navy's Royal Naval Air Service
British Prime Minister, David Lloyd George, wins general election at the head of a national government
Allied forces advance, using the support of tanks for the first time.
Battle of Flers-Courcelette on the Somme
First Indian Army contingent leaves India to serve in France
Daylight raid on London by 18 German Gotha bombers kills 157 people and injures 432
General Ferdinand Foch launches his first counter-attack after five concerted German offensives. The Allied armies take the initiative. Fighting on the Marne continues until 7 August.
Indian infantry begins to leave France in order to transfer to Mesopotamia
Major Anglo-French offensive launched in Picardy. On the opening day, the British Army suffers 57,470 casualties, including 19,240 killed – its heaviest ever casualty toll in a 24 hour period. The battle continues until 18 November.
German airships raid Paris for the first time
Bulgaria declares war on Serbia and enters the war on the side of Germany, Austria-Hungary and Turkey
Women's Auxiliary Army Corps renamed Queen Mary's Auxiliary Army Corps in recognition of their conduct during the German offensive the previous month
Turkish troops in Mesopotamia surrender.
Turkey signs an armistice with the Allies
After their defeat at Ctesiphon, Anglo-Indian troops fall back on Kut al Amara where they are surrounded by Turkish forces. They eventually surrender on 29 April 1916.
On the Salonika front, Alllies begin an attack that leads to the capture of Doiran. Fighting continues to 24 September.
Arab Revolt against Turkish rule launched in the Hejaz region of Arabia by Sherif Hussein of Mecca
Prince Max von Baden becomes German Chancellor
Britain forms the Mediterranean Expeditionary Force under General Sir Ian Hamilton to carry out military operations at the Dardanelles
Germans and Austro-Hungarians launch a major offensive against the Russians
Allied troops in France begin an assault on the German Hindenburg Line. Fighting continues until 9 October.
British troops enter Basra in Mesopotamia at the head of the Persian Gulf
Pact of London signed by the Allied powers of France, Britain and Russia, in which all three agree not to sign a separate peace
The First Defence of the Realm Act (DORA) is passed by the British parliament, giving the government widespread new powers over people's lives
Over 57,000 women enrol in the WAAC, with 9,000 serving in France.
Women's Auxiliary Army Corps (WAAC) formed in Britain, offering women the chance to serve directly in the armed forces
At Salonika Allied troops launch an attack as a prelude to a wider spring offensive in the Balkans. Continues until 22 May.
Advancing Russian troops drive back German forces in East Prussia.
Advancing Turkish forces defeated in the Sinai Desert by Australian, New Zealand and British troops from Egypt. Turks begin to fall back towards Palestine.
General Sir Ian Hamilton is replaced in command at Gallipoli by General Sir Charles Monro
Pope Benedict XV issues call for peace to all those fighting
First battalion of British part-time territorial troops, the 1/14th Battalion, London Regiment –known as the London Scottish– lands in France
Daylight Saving (British Summer Time) introduced in Britain for the first time to encourage longer working hours in factories and on farms
Heavy rain falls across the Ypres battlefields for almost the whole month, preventing any progess
Fourth German offensive (Operation Gneisenau), hitting the French line again, this time south of Verdun near St Mihiel. Fighting continues until 14 June.
Russian Army invades East Prussia in a quick strike against Germany
Baghdad captured by British forces in Mesopotamia
On the Eastern Front, Germans use asphyxiating gas in artillery shells for the first time at the Battle of Bolimov
Britain and France declare war on Turkey
The Germans launch a strong offensive in France (Operation Michael) aimed at splitting the British and French lines. The British in particular suffer heavy casualties and begin a far reaching withdrawal. Fighting continues to 5 April.
Considered finally ready for battle, US 1st Division sent to join French Fifth Army
Fort Douamont captured at Verdun by the Germans
Conscription bill passed by the Canadian parliament
Germany's top air ace, Freiherr Manfred von Richtofen, shot down and killed on the Somme
First Canadian and Newfoundland troops arrive in Britain
Georges Clemenceau becomes Prime Minster and Minister of War in France
Battle of the Somme ends in snow and heavy rain after 142 days of fighting
Hungary is to remain as a separate kingdom.
Austro-Hungarian government announces the country is to become a federal nation based on its many nationalities
British Prime Minister, David Lloyd George, rejects the German peace note and the offer of talks
Begins nearly three years of increasingly bitter confrontation that ends with the formation of the Irish Free State in 1921.
Irish independence declared by Sinn Fein MPs at an unofficial Irish parliament in Dublin
American troops launch a successful attack against the German lines south of Verdun.
Britain declares the North Sea to be a 'military zone', effectively beginning a distant blockade of Germany
German South-West Africa surrenders to South African forces led by General Louis Botha
United States of America declares war on Germany and sides with the Allies
33,204 men enlist on this day, almost the entire number of men recruited in a year before the war (35,000).
High point of British voluntary recruitment
General Max von Prittwitz replaced in command of the German Army in East Prussia by General Paul von Hindenburg, with General Erich Ludendorff as his chief of staff
Renewed attack by British, Australian and New Zealand troops towards Passchendaele begins steady advances in dry weather.
Later the site of the great Memorial to the Missing.
Village of Thiepval captured on the Somme
Bombardment of Scarborough, Hartlepool and Whitby on the British east coast by German battlecruisers
Fighting begins for British troops around the Belgian town of Mons. The BEF begins to retreat alongside its French allies.
Food shortages in Germany and Austria-Hungary, caused by the British blockade and the harsh winter, cause widespread hardship and starvation
General Erich Ludendorff resigns as the German army's Chief Quartermaster General
Fort Vaux captured at Verdun by the Germans
National Registration Act introduced in Britain, obliging all elgible men to register for military service
London Stock Exchange reopens for the first time since the outbreak of war
Portuguese troops see action on the Western Front for the first time
Using tanks, aircraft and artillery a major advance is made into the Hindenburg Line.
German armies stop Franco-British counter-attack astride the River Aisne. The first trenches begin to appear in France. The battle lasts until 15 September.
In northern Palestine, Allied troops launch a devastating attack on the Turks and begin a steady advance into Syria. Fighting continues until 25 October.
In 1914, Italy had been a member of the Triple Alliance with Germany and Austria-Hungary.
Italy signs the Pact of London, effectively joining the war on the Allied side
It lasts until 1 May and is suppressed by the British authorities. The leaders are executed, causing deep resentment.
Irish republicans launch an uprising in Dublin
Public campaign launched in Britain to encourage people to eat less bread as a result of shortages
After the explosion of 19 huge mines, British, Irish, Australian and New Zealand troops seize the Messines Ridge south of Ypres. Fighting continues until 14 June.
1198 people are killed, including 128 US citizens.
German submarine U-20 sinks the luxury passenger liner Lusitania off the west coast of Ireland
Part of the BEF fights a rearguard action against the Germans to allow the main retreat to continue.
Further gains follow, including the cities of Beirut, Homs and Aleppo.
Australian and British troops, supported by Arab forces, capture Damascus in Syria
First members of the WAAC arrive in France