Battle of the Heligoland Bight: 50 Me 109s and Me 110s destroy 12 of 22 Wellington bombers despatched on armed reconnaissance to Wilhelmshaven. Four fighters destroyed. RAF Bomber Command abandoned daylight raids until April 1940.
Winter War: Renewed bombing of Helsinki and shelling of coastal batteries.
Atlantic: Commodore Harwood – victor in River Plate action – promoted to Rear-Admiral and knighted.
1,039 officers and men from scuttled pocket-battleship Admiral Graf Spee interned in Buenos Aires. Captain Langsdorff commits suicide, night December 19-20.