January 17, 1915 – The initial Turkish offensive into Russia is thwarted as the Turkish 3rd Army suffers a defeat by the Russian Army of the Caucasus near Kars. The Russians then begin a multi-pronged invasion of the Ottoman Empire from the Caucasus.
January 19, 1915 – Germany begins an aerial bombing campaign against Britain using Zeppelins.
January 31, 1915 – Poison gas is used for the first time in the war as Germans on the Eastern Front attack Russian positions west of Warsaw. Although the Germans fire 18,000 gas shells, they have little effect on the Russians as frigid temperatures prevent the gas from vaporizing.