January 1 – The British Royal Army Medical Corps carries out the first successful blood transfusion, using blood that had been stored and cooled.
January 10 – In the Erzurum Offensive, Russia inflicts a defeat on the Ottoman Empire.
January 13 – Ottoman Empire forces defeat the Allied British in the Battle of Wadi.
February 11 – Emma Goldman is arrested for lecturing on birth control in the United States.
February 12 – At The Battle of Salaita Hill, South African and other British Empire troops fail to take a German East African defensive position.
February 21 – The Battle of Verdun begins in France.
March 8 – Pancho Villa leads 500 Mexican raiders in an attack against Columbus, New Mexico, killing 12 U.S. soldiers. A garrison of the U.S. 13th Cavalry Regiment fights back and drives them away.
March 24 – French ferry SS Sussex is torpedoed by SM UB-29 in the English Channel, with at least 50 killed, including the composer Enrique Granados.
April 11 – The Egyptian Expeditionary Force begins the occupation of the Sinai Peninsula.
April 24 – The Easter Rising begins in Ireland. Members of the Irish Republican Brotherhood proclaim an Irish Republic, and the Irish Volunteers and Irish Citizen Army occupy the General Post Office and other buildings in Dublin.
April 27 – The 47th Brigade, 16th (Irish) Division at Hulluch in France is decimated, in one of the most heavily concentrated German gas attacks of the war.
April 29 – The Easter Rising ends, as republican commanders issue an order for all companies to surrender.
April 29 – The Siege of Kut ends with the surrender of British forces to the Ottoman Empire, at Kut-al-Amara on the Tigris in Basra Vilayet.
May 16 – Britain and France conclude the secret Sykes–Picot Agreement, which is to divide Arab areas of the Ottoman Empire into French and British spheres of influence.
May 16 – United States Marines invade the Dominican Republic.
May 31 – The Battle of Jutland, between the British Royal Navy and the Imperial German Navy, the war’s only large-scale clash of battleships, begins – the result is inconclusive.
June 4 – The Brusilov Offensive, the height of Russian operations in the war, begins with their breaking through Austro-Hungarian lines.
June 5 – HMS Hampshire sinks, having hit a mine off the Orkney Islands, Scotland, with Lord Kitchener aboard.
June 10 – The Arab Revolt against the Ottoman Empire is formally declared by Hussein bin Ali, Sharif of Mecca.
July 1 – On the first day of The Battle of The Somme around 30,000 British, French and German soldiers are killed
July 15 – Battle of Delville Wood – 766 men from the South African Brigade are killed, in South Africa’s biggest loss during the First World War.
July 29 – In Ontario, Canada, a lightning strike ignites a forest fire that destroys the towns of Cochrane and Matheson, killing 233.
July 30 – German agents cause the Black Tom explosion in Jersey City, New Jersey, an act of sabotage destroying an ammunition depot and killing at least 7 people.
August 5 – At the Battle of Romani British Imperial troops secure victory over a joint Ottoman-German force.
September 6 – The first true self-service grocery store, Piggly Wiggly, is founded in Memphis, Tennessee, by Clarence Saunders.
September 11 – A mechanical failure causes the central span of the Quebec Bridge to crash into the Saint Lawrence River for the second time, killing 13 workers.
September 13 – Mary, a circus elephant, is hanged in the town of Erwin, Tennessee for killing her handler, Walter ‘Red’ Eldridge.
September 15 – Battle of Flers–Courcelette – significant for the first use of the tank in warfare and for the debut of the Canadian and New Zealand Divisions in The Somme.
September 27 – Iyasu V of Ethiopia is deposed in a palace coup, in favour of his aunt Zewditu.
October 21 – Friedrich Adler shoots and kills Count Karl von Stürgkh, Minister-President of Austria.
November 5 – An armed confrontation in Everett, Washington, between local authorities and members of the Industrial Workers of the World results in seven deaths.
November 7 – In The U.S. presidential election, Democratic President Woodrow Wilson narrowly defeats Republican Charles E. Hughes.
November 7 – Republican Jeannette Rankin of Montana becomes the first woman elected to the United States House of Representatives.
November 18 – After 5 months and nearly half a million British casualties, BEF commander Douglas Haig calls off the Battle of the Somme.
November 21 – Emperor Franz Joseph I of Austria dies of pneumonia at the Schönbrunn Palace, Vienna, aged 86, after a reign of 68 years and is succeeded by his grandnephew Charles I.
November 23 – Bucharest, the capital of Romania, is occupied by troops of the Central Powers.
December 12 – ‘White Friday’ in the Dolomites – 100 avalanches bury 18,000 Austrian and Italian soldiers.
December 18 – The Battle of Verdun ends in France with German troops defeated.
December 22 – The British Sopwith Camel aircraft makes its maiden flight. It is designed to counter the German Fokker aircraft.
December 30 – The mystic Grigori Rasputin is murdered in Saint Petersburg.