January 9 – At the Battle of Rafa, the last substantial Ottoman Army garrison on the Sinai Peninsula is captured by the Egyptian Expeditionary Force
January 11 – Unknown saboteurs set off the Kingsland Explosion, one of the events leading to United States involvement in WWI
January 19 – A blast at a munitions factory in London kills 73 and injures over 400
January 25 – British armed merchantman SS Laurentic is sunk by mines off Lough Swilly (Ireland), with the loss of 354 of the 475 aboard
February 13 – Mata Hari is arrested in Paris for spying
February 24 – US ambassador to the UK Walter Hines Page is shown the intercepted Zimmermann Telegram, in which Germany offers to give the American Southwest back to Mexico
March 8 – The February Revolution begins in Russia – Women calling for bread in Petrograd start riots, which spontaneously spread throughout the city
March 15 – Emperor Nicholas II of Russia abdicates his throne and his son’s claims. This is considered to be the end of the Russian Empire, after 196 years
March 26 – At the First Battle of Gaza, British Egyptian Expeditionary Force troops virtually encircle the Gaza garrison, but are then ordered to withdraw, leaving the city to the Ottoman defenders
April 6 – The United States declares war on Germany.
April 9 – At The Battle of Arras, British Empire troops make a significant advance on the Western Front but are unable to achieve a breakthrough.
April 17 – The Egyptian Expeditionary Force begins the Second Battle of Gaza, a frontal attack on Ottoman defenses, which results in 10,000 casualties, and the beginning of the Stalemate in Southern Palestine.
June 7 – The Battle of Messines opens with the British Army detonating 19 ammonal mines under the German lines, killing 10,000 in the deadliest deliberate non-nuclear man-made explosion in history.
July – The first Cottingley Fairies photographs are taken in Yorkshire, England, apparently depicting fairies (a hoax not admitted by the child creators until 1981).
July 6 – At the Battle of Aqaba, Arabian troops, led by T. E. Lawrence, capture Aqaba from the Ottoman Empire.
July 28 – The Silent Parade is organized by the NAACP in New York City, to protest the East St. Louis riot of July 2, as well as lynchings in Tennessee and Texas
July 31 – The Battle of Passchendaele – Allied offensive operations commence in Flanders.
August 18 – The Great Thessaloniki Fire in Greece destroys 32% of the city, leaving 70,000 homeless.
September 23 – Leon Trotsky is elected Chairman of the Petrograd Soviet.
October 12 – At the First Battle of Passchendaele, Allies fail to take a German defensive position, with the biggest loss of life in a single day for New Zealand, over 800 of whose men are killed, roughly 0.1% of the nation’s population
October 13 – The Miracle of the Sun is reported at Fátima, Portugal.
October 24 – At the Battle of Caporetto Austrian and German forces penetrate Italian lines as far south as the Piave River.
October 26 – Brazil declares war against the Central Powers.
October 31 – At the Battle of Beersheba, the British XX Corps and Desert Mounted Corps (Egyptian Expeditionary Force) attack and capture Beersheba from Ottoman forces, ending the stalemate in Southern Palestine.
November 2 – British Foreign Secretary Arthur Balfour makes the Balfour Declaration, proclaiming British support for the “establishment in Palestine of a national home for the Jewish people”
November 6 – Second Battle of Passchendaele – After 3 months of fierce fighting, Canadian forces take Passchendaele in Belgium. The battle concludes on November 10
November 7 – The British Army XXI Corps occupies Gaza, after the Ottoman garrison withdraws.
November 7 – The workers of the Petrograd Soviet in Russia, led by the Bolshevik Party and leader Vladimir Lenin, storm the Winter Palace and successfully destroy the Kerensky Provisional Government.
November 7 – Women win the right to vote in New York State.
November 13 – Battle of Mughar Ridge – The Egyptian Expeditionary Force attacks retreating Yildirim Army Group forces, resulting in the capture of 10,000 Ottoman prisoners, 100 guns and 50 miles of Palestine territory.
November 15 – ‘Night of Terror’ in the United States – Influential suffragettes from the Silent Sentinels are deliberately subjected to physical assaults by guards while imprisoned.
November 15 – The Parliament of Finland passes another ‘Sovereignty Act’, dissolving Russian sovereignty over Finland and effectively declaring Finland independent.
November 17 – US Navy destroyers USS Fanning and USS Nicholson capture Imperial German Navy U-boat SM U-58 off the south-west coast of Ireland, the first combat action in which U.S. ships take a submarine (which is then scuttled).
December 9 – The British Egyptian Expeditionary Force accepts the surrender of Jerusalem by the mayor, Hussein al-Husayni, following the effective defeat of the Ottoman Empire’s Yildirim Army Group.