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| 1915, Jan |
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| Defeat of the Ottomans in the Caucasus at the Battle of Sarikamish. The victorious Russian forces advanced and took the fortress of Erzurum on Feb. 15. | 1 |
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| Feb. 3–4 |
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| Failed Ottoman attack on the Suez Canal. | 2 |
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| March 4–April 10 |
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| The Constantinople Agreement. Britain and France formally promised that in the event of a complete Entente victory, Russia would receive Istanbul and the Straits. | 3 |
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| April |
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| Armenian revolt in Van. Russian forces reached the city in May. | 4 |
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| April 25 |
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| Opening of the BATTLE OF GALLIPOLI, which the Entente eventually lost. The British and French landed troops in the Straits with the goal of capturing Istanbul. After suffering heavy losses from fierce Ottoman resistance, they were forced to withdraw (Dec. 1915–Jan. 1916). | 5 |
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| April 26 |
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| The Treaty of London. The British recognized Italian claims to the Dodecanese Islands and the province of Adalya in Anatolia. | 6 |
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