Battle of the River Plate. Graf Spee sails towards the River Plate estuary (separates Uruguay and Argentina) to attack a convoy of 4 ships tought to be leaving Montevideo. Graf Spee’s Captain Hans Langsdorff is acting on information captured from British steamer SS Streonshalh (sunk on Dec 7).
Meanwhile, Royal Navy Force G (light cruisers HMS Ajax and HMS Achilles) is already heading to River Plate, following Commodore Henry Harwood’s hunch that Graf Spee will try the busy shipping lanes of South America. Harwood makes the wise decision to order the heavy cruiser HMS Exeter (currently refitting in Port Stanley, Falkland Islands) to join them in the River Plate estuary. Another heavy cruiser, HMS Cumberland, remains refitting in Port Stanley.
Western Front. Corporal Thomas Priday (King's Shropshire Light Infantry) becomes the first British soldier killed in action in WWII, a victim of “friendly fire” while on patrol.