On this day 17 September 1939
The carrier HMS Courageous was torpedoed and sunk by U-boat 29 - the first Royal Navy warship to be lost in World War II. She capsized and sank within 20 minutes with the loss of over 500 of her crew.
Britain declared war on Germany 3 September 1939. U-29 had previously sunk 3 British merchant ships, Regent Tiger (8 Sep), Neptunia (13 Sep) and British Influence (14 Sep).