Over Germany… The first “area bombing” raid on a German city is carried out: Mannheim is attacked by 134 RAF bombers during the night (December 16-17). Large fires are started on both banks of the Rhine River. Other targets include Speyer-am-Rhein and Heilbronn.

Over Switzerland… Basle is accidentally bombed by the British aircraft, killing 4 persons.

In the Mediterranean… There are further British and Italian fleet operations over the next week. The British carrier Illustrious attacks airfields on Rhodes and sends strikes against Italian convoys.