Diary October 20, 193910-1939, Diary WW2, War Diary, Year 1939 / October 20, 2019 October 20, 2019 / Leave a Comment / By Kretaner / 1 minute of reading Sinking merchantmen after U-boat attack.War Diary for Friday, October 20, 1939: Sea War Atlantic: Germany warns that neutral merchant ships joining Allied convoys will be sunk without warning. for sharing: Share Tweet LinkedIn