The battle that frightened Churchill: the war in the Atlantic

On 3 September 1939, the passenger liner Athenia was sunk by U30.
So began the Battle of the Atlantic, the longest and most complex
campaign of the Second World War. The battle pitted the submariners
of the Kriegsmarine against the Allied merchant fleet who were
providing Britain's vital life line. This talk follows the changes
in fortune of both the Kriegsmarine and the merchant fleet, and
explains why Winston Churchill knew that the Battle of the Atlantic
was the battle that Britain could not afford to lose.