September 1915
| Date | Events |
|---|---|
| 1 | German government accepts United States demands for limitation of submarine activity |
| 5 | Fighting at Hafiz Kor on the North West frontier of India |
| 7 | Russians begin an offensive in Galicia |
| 18 | German forces capture Vilna (Vilnius, now capital of Lithuania) |
| 21 | Bulgarian government orders partial mobilisation of its forces |
| 21 | Greeks ask for guarantee of 150,000 British and French troops as a condition of its intervention in the war: Allies agree (24 September) |
| 22 | Turks and Bulgarians sign an agreement (Dedeagatch Agreement) conceding part of joint frontier to Bulgaria |
| 22 | Allied forces begin a second attempt to advance on Yaunde in the Cameroons |
| 23 | Greek government orders precautionary mobilisation |
| 25 | French forces begin two large offensives in Artois and Champagne |
| 25 | British First Army launches attack between La Bassee Canal and Loos-en-Gohelle - the Battle of Loos - largest British offensive operation to date and first time it deploys poison gas |
| 25 | Bulgarian forces begin mobilisation |
| 26 | Lieut-Gen. Sir A. J. Murray appointed Chief of the Imperial General Staff, replacing Wolfe Murray who had resigned previous day |
| 27 | Greek premier Venizlos obtains secret consent of King Constantine to proposed Allied expedition to Salonika |
| 28 | British and Indian forces engaged in fighting Turks at Kut-al-Amara in Mesopotamia |
| 28 | Greek government refuses Allied offer of troops (made 24 September) even though they had previously requested it |
| 30 | Lord Derby assumes responsibility for recruiting in Britain |