Flanders – BATTLE OF MESSINES RIDGE (until June 14): 9 divisions of British Second Army (Plumer) attack on 9-mile front and capture Messines-Wylschaete ridge. Attack preceded at 0310 hours by devastating, 500t largest non-nuclear explosion of 19 mines (1 still unexploded); causes panic in Lille 15 miles distant. British take 6,400 PoWs. German Gruppe Wytschaete commander Laffert sacked (June 16).
Belgium: Petain impresses King Albert at first meeting, tells him ‘The French Army is no longer what it was’, Belgians to join Anglo-French Flanders advance at certain stage.
Atlantic: U-boats begin offensive off US East Coast. Q-ship Pargust (Campbell, crew win 2 Victoria Cross) sinks UC-29 (Rose) off southeast Ireland.
Baltic: First Congress of the Baltic Fleet (until June 28) at Helsinki tries to clarify C-in-C’s authority.
Western Front: Mannock scores his first victory.