North Sea: Royal Navy’s Room 40 gives early warning of German Fleet sortie and that 16 U-boats on sea. Main body of Grand Fleet (Jellicoe) leaves Scapa and Invergordon at 2200 hours. Battlecruiser Force (Beatty) leaves Rosyth.
Adriatic: Rear-Admiral Mark Kerr takes over British Adriatic Squadron end of May.
Verdun: French withdraw from Bethincourt-Cumieres road and Caurettes Wood, withdraw towards Chattancourt. Later drive Germans back to Cumieres. General Knobelsdorf decides to stick to east bank offensive only despite Gallwitz success on west bank.
France: Heavy artillery production programme begins; 4,690 guns ordered.
Italian Front: Austrian XX Corps secures Mt Pria Fora (5423 ft southwest of Arsiero) after bloody fighting following Italians losing their way and failing to occupy it.
East Africa: 300 Rhodesians capture ‘German bridge’ west of Bwiko which Smuts occupies on May 31 and halts on half rations to ease supply.
Western Front: Rain and low clouds.
France: Great artillery production programme adopted for modernization and motorization.