'Keep memories of Nanjing Massacre alive'

An estimated 300,000 Chinese civilians and unarmed soldiers were killed in the Nanjing Massacre in 1937, in one of the darkest chapters of the Sino-Japanese War and the Second World War.

While the atrocities are well documented, a piece of history relating to the massacre is perhaps less well known.

The Nanjing Safety Zone was set up by a group of foreigners living in the city at the time, providing refuge to terrified residents and saving numerous lives.

And the legacy of their heroics lives on.

Frank Yung spoke to the grandson of an American missionary who shot the only surviving footage of the massacre as well as a historian, and looks at how the memories are being kept alive.