4: The British battleship HMS Nelson is incapacitated for six months by yet another magnetic mine left this time by the U-52 off the Loch Ewe.

13: The battle of the River Plate off Montevideo, Uruguay. The Royal Navy's hunting group F, composed of three cruisers (Exeter, Ajax and Achilles), attacks off the estuary of the River Plate the German warship Admiral Graf Spee and heavily damage it.

17: The Admiral Graf Spee is forced by Uruguay to leave Montevideo harbor; given freedom of choice by Berlin the ship's Kapitän zur See Hans Langsdorff orders to scuttle the vessel just outside the harbor. The ship's captain and its crew are interned by Argentinian authorities.

18: The first Canadian troops arrive in Europe.

18: Germany defeats Britain in the Battle of the Heligoland Bight.

27: The first Indian troops arrive in France.

28: The British Minister of Food W.S. Morrison announced that starting January 8, rationing would be expanded to include butter, bacon, ham and sugar.