Dardanelles: In April first German airmen in action.
Western Front: Lieutenant R Garros of Escadrille MS 23 in Morane ‘N’ shoots down Albatros 2-seater near Dixmude. His 2nd victory follows on April 15, 3rd on April 17. Jean Navarre and Robert in Morane ‘L’ (Ese MS 12) shoot down Aviatik 2-seater near Soissons with rifle fire. French aircraft bomb rail stations and bivouacs at Vignuelles (Champagne) and near Soissons (night April 1/2). In April French introduce Lafay bombsight.
During April first French trench mortar, a 58mm (2.1 in) weapon enters service.
Flanders: Cloister Hoek, near Dixmude, occupied by Germans.
Poland: Russian advance checked in West Poland, but cavalry defeat German cavalry in the North next day.
Serbia: In April 48,000 Serb troops still in hospital with typhus. British 3rd Serbian Relief Fund surgical unit (all women) lands and soon treats 12,000 civilians. Bulgar Komitadjis (Irregulars) attack Serbs at Valandovo.
Armenia: Russians occupy Tsria, defeat Turks at Oltu on April 4.
Mesopotamia: II Indian Corps formed, Nixon replaces Barrett (sick) as C-in-C on April 9.
East Africa: German forces are 2,275 Europeans; 7,647 Askaris; 1,858 others; 32 guns; 78 MGs. British withdraw from Longido until April 11 for rainy season.
Southwest Africa: South African East Force occupies Hasuur and Kalkfontein and Ukamas (April 5), South force occupies Warmbad (April 3). Both forces meet on April 14.
Britain: In April first 50 motor launches (MLs) ordered from Elco, Bayonne, New York. Total 551 built.
Germany: Bismarck’s birth centenary celebrations. Rosa Luxemburg imprisoned in Berlin for attacking Army. State nitrogen plant (175,000t pa capacity) laid down at Piesteritz (Elbe).
Britain: Union unemployment lowest for 25 years.