Dardanelles: HMS Humber first RN monitor to arrive, these shallow-draught heavy-gunned vessels reduce need for more vulnerable battleships.
Persia: German Hentig mission enters bound for Afghanistan and India, reaches Tehran around June 15. 3 other German-led parties reported in June.
Italian Front: Italian airship M2 (Felice di Pisa) shot down by Austrian 2-seater (Kissing and Gronenwald).
USA: Bryan resigns as Secretary of State, unwilling to sign 2nd Lusitania protest note. Lansing succeeds, condemns German accusations.