1915 was a free year.
January 24 - British warships sink the German cruiser "Blicher" in the battle of Doger Bank in the First World War in the North Sea, killing 870 people.
January 28 - By the decision of the American Congress, the US Coast Guard was created as one of the branches of the US Armed Forces.
March 10 - The First Yugoslav People's Assembly is held in Chicago, with representatives of 486 various emigrant organizations from the United States and Canada in favor of the idea of liberating and uniting the South Slavic peoples into one state.
March 14 - The British Navy finds and sinks the German light cruiser SMS Dresden at the Battle of Mas de Thierry.
April 15 - The genocide of Armenians begins with the persecution of Armenian intellectuals in Constantinople.
April 22 - German troops use poison for the first time in World War I on the Western Front near Ypres.
April 25 - Operation Gallipoli, one of the largest battles of the First World War, begins with the landing of British, French, New Zealand and Australian troops on the Gallipoli Peninsula.
April 26 - Italy secretly signs the London Agreement with Great Britain, Russia and France and, in the First World War, sided with the Entente powers, promising to gain Tyrol, Trieste, Gorizia, Istria, parts of Dalmatia and Albania.
May 7 - A German U20 submarine torpedoes the British passenger ship Lusitania, contributing to the US decision to enter World War I.
May 22 - A collision between two trains in Scotland kills 227 people in Britain.
June 5 - Women in Denmark are given the right to vote.
July 21 - Alberta Alcoholic Referendum 1915
5-8. October - Fall of Belgrade 1915
December 12 - President of the Republic of China Yuan Shikai reintroduces the monarchy and proclaims himself King of China.
March 8 - Milica Pavlović Dara, People's Hero of Yugoslavia († 1944).
March 15 - Venko Markovski, Macedonian writer († 1988)
March 23 - Vasily Zaytsev, Soviet sniper († 1991)
May 6 - Orson Welles, American film actor, director and producer († 1985)