World War One Diary for Wednesday, September 19, 1917:
East Africa: Kilwa Force action at Mihambia (until September 20) costs 145 casualties and fails to cut off over 1,100 German troops retreat behind burning grass. British advance resumes on September 24 after thirst quenched.
Baltic: 20 Russian warships at Helsinki raise Red Flag.
Ypres: Sopwith Camel fighter first used as light bombers with four 20lb or 25lb bombs.