A British counter-attack near Vermelles is partially successful.
May 13 (Sat.)
The Germans attack the British at Ploegsteert Wood and are repulsed.
The Caucasus:—The Russians retire on Erzerum.
The British monitor M30 is sunk in action in the Gulf of Smyrna.
May 14 (Sun.)
Italy:—The Battle of the Trentino begins (see June 4).
May 15 (Mon.)
The British capture a German trench on the Vimy Ridge.