ITALY ENTERS WAR. Austrian guns in Carnic Alps fire first shots shortly before midnight.
Flanders: Unsuccessful German counter-attack at Festubert.
Dardanelles: Royal Navy submarine E11 (Nasmith) torpedoes Turk torpedo gunboat Pelngi Deria (salvaged) off Seraglio Point, Constantinople. Then, on May 25, torpedoes Turk transport Stamboul in Constantinople harbour, one of 8 victims on this cruise.
Italy: Italian air force has 6 squadrons of Bleriots, 4 squadrons of Nieuports, 4 squadrons of Farmans (total 79 operational aircraft); also 3 floatplanes.