At the start of 1915, the war had settled into the stalemate of trench warfare on the western front. The German command switched their focus to the eastern front and defending their occupied territory on the western front. Throughout 1915-1916, even more countries would join the already global conflict. The allies would launch multiple major offensives in 1916. These battles would be the biggest of the war and devastatingly demonstrate the war of attrition which the war had descended into.
- 1st - British battleship HMS Formidable is sunk by a German submarine in the english channel.
- Germany is under a British Naval blockade that will severely hamper their war effort. The Germans can only fight back with submarine warfare.
- 8th - The battle of Soissons begins, German and French forces will fight over the French town.
- 14th - Battle of Soissons ends in a stalemate.
- 19th - First German zeppelin bombing raid on England.
- 26th - Turkish advance on Egypt through the Sinai desert begins.
- 3rd - Turkish troops reach the Suez canal. The Suez canal was a vital supply route for the British Empire and a source of oil for mechanised warfare, which was becoming increasingly important.
- 4th - Turkish troops are repelled and retreat back into the Sinai.
- 4th - Germany announces a submarine blockade of Britain, with neutral ships in the firing line.
- 26th - German troops use a flamethrower for the first time. The early flamethrowers were cumbersome and mainly fired from within a trench.
- 10th - The battle of Neuve Chapelle begins, a British offensive in the Artois region.
- 13th - Battle of Neuve Chapelle ends. The British troops broke through the German lines at Neuve Chapelle but were then stopped by German counter attacks.
- 17th - Battle of Hill 60, British troops take the high ground of Hill 60, south-east of Ypres. The small battle is notable for the laying of large mines and subsequent explosions under the German positions.
- 22nd - 2nd Battle of Ypres begins, German troops fought to capture the Belgian town. The campaign will consist of several battles: the battle of Gravenstafel Ridge, the battle of St Julien, the battle of Frezenberg Ridge and the battle of Bellewaarde Ridge.
- 22nd - Battle of Gravenstafel Ridge, German troops release chlorine gas against French territorial and colonial troops. The surprise weapon caused panic, many casualties and broke the French lines. This wasn't foreseen by the Germans and they failed to take advantage.
- The use of chemical weapons was against the Hague convention, which outlawed poisonous gases.
- Canadian troops improvised gas masks by urinating into cloth and holding it over their faces. Effective gas masks would quickly be developed and reduce the effectiveness of gas attacks.
Plainly something terrible was happening. What was it? Officers, and Staff officers too, stood gazing at the scene, awestruck and dumbfounded; for in the northerly breeze there came a pungent nauseating smell that tickled the throat and made our eyes smart. [...] "What's the matter, you bloody lot of cowards?" says he. The Zouave was frothing at the mouth, his eyes started from their sockets, and he fell writhing at the officer's feet.
— Anthony R. Hossack
- 24th - Battle of St Julien begins. Chlorine gas is used again on the new front line held by Canadian troops.
- 25th - British (including a large contingent of ANZAC troops) and French troops land at Gallipoli in Turkey. Their progress is subject to strong resistance and it will soon descend into a futile campaign.
- 26th - Italy secretly signs the Treaty of London to join the war on the side of the allies.
- Italy had refused to join at the start of the war as they claimed the entente as a purely defensive alliance.
- The Italians negotiated with both sides and were swayed by promised territory, particularly from Austria-Hungary.
- 1st - Battle of Gorlice-Tarnow begins, Germany supports Austro-Hungary in an offensive to relieve pressure on the south of the eastern front.
- 4th - Italy denounces the triple alliance.
- 4th - Battle of St Julien ends.
- 5th - Battle of Gorlice-Tarnow ends, the central powers had broken through the Russian trench lines.
- 7th - RMS Lusitania, a large passenger ship, is sunk by a German submarine. There are 1198 deaths, including 128 Americans. Incidents such as this are turning US opinion, which was pretty evenly split at the start of the war.
- 9th - Second battle of Artois begins.
- 23rd - Italy starts mobilisation and declares war on Germany and Austro-Hungary.
- 24th - Italian forces cross the Austrian frontier.
- 24th - Entente governments declare they will hold Turkish ministers responsible for Armenian massacres.
- The systematic extermination of 1.5 million Armenians by Turkey will later be classified as a genocide.
- 25th - Battle of Ypres ends in a stalemate.
- 5th - First meeting of British and French ministers to coordinate war strategy.
- 18th - Second battle of Artois ends, the French had advanced the front by 3 km at a huge cost.
- 23rd - The first battle of the Isonzo fought between Italian and Austro-Hungarian forces. The mountainous territory produces perhaps the toughest conditions the war will be fought in.
- There will be eleven battles of the Isonzo in an exhaustive campaign with little changes in territory but massive degradation of the two armies.
- 13th - Austro-German forces launch an offensive across the Eastern front. This is also known as the great retreat, with Russian forces being pushed out of Poland and into Russia. This new frontline would remain relatively stationary until the end of the war.
- 20th - Battle of Le Linge begins, the French carry out an offensive in the Vosges Mountains. The German positions were heavily reinforced with tunnels and concrete and hence the fighting was vicious.
- 5th - Warsaw occupied by German forces.
- 6th - More troops are landed at Gallipoli but they fail to make a breakthrough.
- 21st - Italy declares war on Turkey.
- 5th - Tsar Nicholas II (the Russian Emperor) puts himself in supreme command of the Russian armies.
- 25th - Bulgarian mobilisation begins.
- 25th - An allied autumn offensive begins. The French army would attack the German defenses in the second battle of Champagne and the third battle of Artois. British forces would also attack at the Battle of Loos.
- At the battle of Loos, Britain would use poison gas for the first time. Results were mixed with the gas being blown back by the wind towards some sections of the British line.
- German aircraft were the first to fit an interrupter gear. This synchronised the firing of front mounted machine guns with the timing of the aeroplane's propeller.
- The Germans had gained a mastery of the air and prevented the allies from gaining vital reconnaissance.
- 5th - Allied troops are landed at Salonika, Greece. The troops were too late to save Serbia but remained in Salonika. This was a source of major political contention in Greece which had pro entente and pro alliance factions.
- 6th - The final invasion of Serbia begins by Austro-German forces.
- 8th - Battle of Loos ends, the British advances were contained except for local losses of ground.
- 9th - Belgrade is taken by Austrian forces.
- 10th - The Greek government reject serbian claims for help and retain a policy of armed neutrality.
- 14th - Bulgaria and Serbia declare war on each other. Bulgarian forces invade Serbia.
- With the overwhelming manpower, Serbia will be quickly lost to the alliance forces. A small amount of Serbian troops will escape to Salonika.
- 15th - Third battle of Artois ends.
- The German army is developing its defense in depth tactics. The front line would be defended lightly, allowing attacking forces to advance. The heavy defenses would be placed further back, out of artillery range, would then be used to decimate the attacking forces.
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- 6th - Second battle of Champagne ends.
- 11th - First British advance on Baghdad begins.
- 22nd - Battle of Ctesiphon begins, with Turkish forces set up to halt the the British advance.
- 25th - Battle of Ctesiphon ends with the British forces retreating to the town of Kut.
- 30th - Serbian retreat through Albania begins.
- 7th - Kut is besieged by Turkish forces.
- Kut would eventually fall with the loss of 30,000 British-Indian troops, one of the worst allied defeats of the war.
- 19th - The evacuation of Gallipoli begins. The evacuation will take place over December and early January of 1916.
- The Gallipoli evacuation was hidden from the Turkish forces through various techniques, including self-firing rifles that were rigged to fire automatically. The evacuation was the only success of the Gallipoli campaign.
- 8th - Evacuation of Gallipoli is completed.
- 27th - The military service act is passed by British parliament. This introduced conscription for unmarried, 18-41 year old men.
- Food shortages are getting serious in Germany. Substitute foodstuffs became commonplace and the German people would steadily become more malnourished.
- 21st - The battle of Verdun begins. Verdun was a fortified French town, containing multiple forts and is a symbol of French national pride. The German plan was to bleed the French army of its men in a location which they, correctly, assumed would be defended at all costs by the French command.
- The fierce fighting at Verdun will rage throughout most of the year.
- 9th - Germany declares war on Portugal.
- Although Portugal was neutral, there had been clashes between Portuguese and German colonial troops in Africa. The German submarine campaign was also disrupting Portuguese trade with Great Britain.
- 15th - Austria-Hungary declares war on Portugal.
- Advancements in the French air force and the British RFC (royal flying corps) end the period of German air superiority over the western front.
- 4th - General Brusilov is appointed to command the Russian southern armies.
- 24th - Outbreak of the easter rising in Ireland. Irish republicans in Dublin start an armed insurrection against British rule of Ireland, while the British army is busy at war.
- 27th - Martial law is declared in Dublin, Ireland.
- 1st - The Irish rebels surrender. The British troops had been greater in number and even brought in artillery to crush the rebellion.
- 21st - German forces attack and capture Vimy Ridge. British troops had recently been moved in to relieve the French forces, which were needed at Verdun.
- 31st - The battle of Jutland begins, it will be the largest naval battle of the war. The Germans tried to trap a scouting group of the main British fleet. Eventually, this leads to both fleets directly clashing.
- Jutland would be the last major clash of battleships in history.
- 1st - Battle of Jutland ends. Both sides have lost large numbers of ships and men. The Germans have suffered less casualties but their fleet won't try and challenge the British fleet for the rest of the war.
- 4th - The Brusilov offensive begins, a large Russian offensive to try and relieve pressure from the French at Verdun.
- Although the offensive isn't a complete success, the attacks coordinated by general Brusilov make large breakthroughs. This the biggest Russian success of the war and cripples the Austro-Hungarian army.
- 1st - Battle of the Somme begins, British and French forces will attack German lines along the Somme river. Land will be slowly gained at huge costs.
- British casualties will almost reach 60,000 on the first day of the Somme; this is the worst day in the history of the British army.
- The somme battle will be the bloodiest battle on the western front.
- 4th/5th - The Battle of Rumani, this is the final attack by Ottoman and German forces on the Suez canal. British Empire forces successfully repel the attacking forces.
- 27th - Romania begins mobilisation and declares war on Austria-Hungary.
- 28th - Germany declares war on Romania.
- The Romanians were impressed by the Brusilov offensive and wanted the Transylvania region from the Austro-Hungarian Empire.
- The Romanian army immediately began an invasion of Transylvania and would be initially successful. However, they would be pushed back from later counter attacks.
- 30th - Turkey declares war on Romania.
- 1st - Bulgaria declares war on Romania.
- 15th - 22nd - The Battle of Flers-Courcelette takes place as part of the Somme campaign. This is notable for the first use of tanks by the British army.
- The tanks are used in small numbers and prove unreliable, which means their success is limited.
- 20th - Brusilov offensive ends. The overall campaign was costly for the Russian army and it was no longer able to launch large offensives.
- 14th - German forces cross the Transylvanian frontier of Romania.
- 18th - The battle of the Somme ends after four and a half months of fighting. Combined casualties exceed 1.2 million.
- Both sides took their share of heavy casualties and the allies only managed to advance their frontline by 10km.
- However, this battle can be seen as a turning point of the war. Great Britain's economy was out producing the German's and this was seen with an increased number of British shells. British commanders were also starting to develop combined arms warfare. The creeping barrage was beginning to be used, aircraft were now coordinating with infantry and tanks were introduced.
- 21st - Emperor Franz Joseph of Austria-Hungary, aged 86, dies and is succeeded by Archduke Karl, aged 29.
- 23rd - A Greek provisional government, at Salonika, declares war on Germany and Bulgaria.
- 4th - Herbert Asquith resigns as British prime minister. He will be replaced by the war secretary, Lloyd George.
- 6th - Bucharest, capital of Romania, capitulates to German forces.
- 12th - Germany proposes peace talks through the USA, no conditions or details are proposed.
- The Entente powers reject the offer. They have sacrificed too much and want a German defeat.
- 18th - The battle of Verdun ends. The German command had underestimated the French resolve and Verdun was held. Verdun inflicted over 540,000 French casualties but the Germans also suffered with over 400,000 casualties.
- 29th - Siberian monk Rasputin is assassinated in Petrograd. The assassins wanted to end Rasputin's influence over the Tsar.
- 30th - British and Chinese governments reach an agreement over chinese labourers. Chinese labourers will work in support roles and perform manual labour on the western front.
 World War 1 Timeline, The Great War, URL: http://www.greatwar.co.uk/timeline/ww1-timeline.htm
 World War 1 Timeline, Alpha History, URL: http://alphahistory.com/worldwar1/world-war-i-timeline/
 R. Holmes, The First World War in Photographs, Carlton Books (2001)
 Z. Beauchamp, T. B. Lee & M. Yglesias, 40 maps that explain World War 1, Vox (August 2014), URL: http://www.vox.com/a/world-war-i-maps
 M. Harrison, Why the Battle of the Somme marks a turning point of World War 1, The Conservation (June 2016), URL: http://theconversation.com/why-the-battle-of-the-somme-marks-a-turning-point-of-world-war-i-60741
© 2017 Sam Brind