USA: Government dissatisfied with German Lusitania reply. British Ambassador says Lusitania never carried guns (untrue).
Germany: Baron Wangenheim cables Berlin on need to ‘mitigate’, but not hinder measures against Armenians.
Despite Allied attacks, Germans send 2 divisions during May to Eastern Front. BEF May loss of 65,730 soldiers, worst until July 1916. Souchez sugar refinery stormed by French.
Poland: German Ninth Army gas attack north of Bolimow until next day causes 1,000 Siberian VI Corps casualties; but 56 Germans also gassed.
Galicia: Mackensen storms 3 forts north of Przemysl; Südarmee takes Stryj. Russian Southwest Front losses 412,000 (153,000 PoWs) men and 300 guns.
Trentino: By now elite Bavarian Alpenkorps (13 battalions, 11 MG coys, 36 guns) reinforces Austrian First Army (Dankl) in this sector.
Gallipoli: GHQ lands at Imbros island; 38,000 Allied casualties to date.
Mesopotamia – Second Battle of Qurna: ‘Townshend’s Regatta’ with 372 local bellum boats (2,560 infantry, 17 guns) and 7 Royal Navy vessels beats Halim Bey’s Turks, taking 4 hills, 3 guns and 271 PoWs for 24 casualties.
North Cameroons: 1,834 Allies, 71 guns and 12 MGs surprise bombard Garua until June 10.
Britain: Royal Flying Corps casualties to date 134 men, strength 5,147 men in 23 squadrons. So far 530 aircraft brought into service; c.300 lost or worn out; 2,260 on order from 31 firms. 234 RFC pilots and observers training at 11 stations.
Army Zeppelin LZ38 drops 120 small bombs on East London (42 casualties, £18,596 damage) and at 10,000 ft evades 15 defence sorties (1 Vickers Gunbus crashes, night May 31- June 1).