As seen on Wikipedia:
https://en.wikipedia.org/wiki/John_KeransAs Assistant British Naval Attaché in then Nanking, China in 1949, Lieutenant-Commander Kerans took command of
HMS Amethyst when the ship came under fire on the Yangtze River during the final stages of the Chinese Civil War after the captain and 16 others were killed in the shelling. The ship was detained for ten weeks during negotiations for its release, until Kerans led a night-time escape. Kerans was awarded the Distinguished Service Order. The Amethyst incident was later the subject of a film entitled Yangtse Incident: The Story of
HMS Amethyst (1957), in which Kerans was portrayed by the British actor Richard Todd.