January 1 – The St. Petersburg–Tampa Airboat Line in the United States starts services between St. Petersburg and Tampa, Florida, becoming the first airline to provide scheduled passenger services
January 9 – The Phi Beta Sigma fraternity is founded by African American students at Howard University, in Washington, D.C
February 2 – Charlie Chaplin makes his film début, in the comedy short Making a Living
March 10 – Suffragette Mary Richardson damages Velázquez’ painting Rokeby Venus in London’s National Gallery, with a meat chopper
March 16 – Henriette Caillaux, wife of French minister Joseph Caillaux, murders Gaston Calmette, editor of Le Figaro, fearing publication of letters showing she and Caillaux were romantically involved
April 4 – The Komagata Maru sails from India to Canada. Due to Canadian regulations designed to exclude Asian immigrants, the boat is forced to return to Calcutta with all its passengers
April 9 – A misunderstanding involving US Navy sailors in Mexico and army troops loyal to Mexican dictator Victoriano Huerta leads to a breakdown in diplomatic relations between the United States and Mexico
April 20 – The Colorado National Guard attacks a tent colony of 1,200 striking coal miners in Ludlow, Colorado, killing 24 people
April 21 – 2300 U.S. Navy sailors and Marines from the South Atlantic fleet land in the port city of Veracruz, Mexico, which they will occupy for over six months
June 12 – Ottoman Greeks in Phocaea are massacred by Turkish irregular troops
June 28 – Serbian nationalist Gavrilo Princip assassinates Archduke Franz Ferdinand of Austria and his wife, Duchess Sophie, in Sarajevo.
June 29 – Anti-Serb riots in Sarajevo and Zagreb break out
July 23 – Austria-Hungary presents Serbia with an unconditional ultimatum.
July 28 – Austria-Hungary declares war on Serbia by telegram. Tsar Nicholas II of Russia orders a partial mobilisation against Austria-Hungary.
July 28 – British and French naval forces fail to prevent the ships of the Imperial German Navy Mediterranean Division from reaching the Dardanelles.
August 1 – Germany declares war on Russia, following Russia’s military mobilization in support of Serbia. Germany also begins mobilisation.
August 2 – German troops occupy Luxembourg
August 4 – German troops invade Belgium at 8.02 am. In London the King declares war on Germany for this violation of Belgian neutrality and to defend France
August 5 – The German Army overruns and defeats the Belgians at Liège with the first operational use of Big Bertha (a howitzer).
August 7 – France launches its first attack of the war, in an ultimately unsuccessful attempt to recover the province of Alsace from Germany, beginning the Battle of the Frontiers.
August 17 – The Battle of Tannenberg begins between German and Russian forces.
August 23 – In its first major action at the Battle of Mons, the British Expeditionary Force holds the German forces, but then begins a month-long fighting Great Retreat to the Marne.
August 24 – Serbian troops defeat the Austro-Hungarian army at the Battle of Cer, marking the first Entente victory of the War.
August 27 – At the Battle of Le Cateau, British, French and Belgian forces make a successful tactical retreat from the German advance.
August 28 – At Heligoland Bight British cruisers under Admiral Beatty sink three German cruisers.
August 30 – At The Battle of Tannenberg, The Russian Second Army is surrounded and defeated.
September 5 – The First Battle of the Marne begins when French 6th Army attacks German forces near to Paris. Over 2 million fight, and a quarter are killed or wounded
September 22 – German submarine U-9 torpedoes three British Royal Navy armoured cruisers, HMS Aboukir, Cressy and Hogue, with the death of more than 1,400 men, in the North Sea.
October 9 – Antwerp (Belgium) falls to German troops.
October 19 – The First Battle of Ypres begins.
October 31 – At The Battle of the Yser, the Belgian army halts the German advance, but with heavy losses
October 31 – The Battle of the Vistula River concludes in Russian victory over German and Austro-Hungarian forces around Warsaw.
November 5 – After the shelling of Russian Black Sea ports, Britain and France declare war on The Ottoman Empire
November 7 – The Japanese and British seize Jiaozhou Bay in China, the base of the German East Asia Squadron at Tsingtao.
December 2 – Austro-Hungarian forces occupy the Serbian capital of Belgrade.
December 19 – The Battle of Kolubara ends, resulting in a decisive Serbian victory over Austria-Hungary.
December 24 – An unofficial, temporary Christmas truce begins, between British and German soldiers on the Western Front.