Cunard passenger liner Athenia of 13,581 tons,
German submarine U-30 (Oblt. Fritz-Julius Lemp) on the opening day of the Second World War, the captain believing it to be an armed merchant cruiser.
The ship was carrying evacuees from Liverpool to Canada. There were 1,103 passengers not including crewmembers. Survivors were rescued by the British destroyers Electra, Escort and Fame and the freighters City of Flint and Southern Cross, but 118 passengers were drowned. Also on board were 316 Americans of whom 28 were lost. Oblt. Lemp was never court-martialled for this error but next day Hitler ordered that under no circumstances were attacks to be made on passenger ships.
And a pic:
