North Sea – Only British air kill of a U-boat: Royal Navy Air Service H12 America flying boat (Flt sub-lt N Magor) bombs coastal submarine UB-32.
Channel: Dover Patrol monitor Terror shells Ostend (35 shells), sinks floating dock (and on September 25).
Atlantic: Convoys from Dakar start.
East Africa – Battle of Bweho Chini: over 1,100 German troops and over 20 MGs (estimate over 340 casualties) just fail to storm surrounded Nigerian Brigade camp (134 casualties). Kilwa Force reunited on September 24. Belgians fight at Hyka on river M’kaha.
North Sea: 3 Royal Navy Air Service Sopwith Camel fighters over Dover Patrol destroy, force down or capture 4 German seaplanes from Ostend and Zeebrugge (and on September 25).
Germany: French raid Stuttgart, Trier, Koblenz and Frankfurt.