June 4 (Mon.)
Resignation of General Alexeieff as Russian Commander-in-Chief; he is succeeded by General Brussiloff (see Aug. 1).
June 5 (Tues.)
An action at long range between British light cruisers and destroyers, under Commodore Tyrwhitt, and six German destroyers; one German destroyer, the S20, is sunk by gunfire.
Ostend is bombarded by British naval forces.
A daylight raid by 18 German aeroplanes on the south-eastern counties of England; two German aeroplanes are destroyed.
June 7 (Thur.)
A British offensive is launched between Ypres and Armentières (the Battle of Messines; see June 14): an attack in strength on the Messines-Wytschaete Ridge is preceded by the explosion of 19 mines; Messines, the Messines Ridge, the village of Oosttaverne, and the enemy's positions on a front of 9 miles are captured, with 7000 prisoners and many guns.
June 8 (Fri.)