More than a third of the 35,000 US servicemen in Japanese captivity died, having been beaten, starved, dehydrated, made to take part in medical experiments or forced into slave labour. This compared to the American death rate in German PoW camps of barely one per cent. But in spite of his dehumanising treatment, Zamperini could be counted lucky: his modest fame as an Olympian and his consequent potential as a propaganda tool almost certainly saved his life when he was captured after nearly seven weeks adrift as a castaway and held at Kwajalein, a Japanese-held atoll in the Marshall Islands known as Execution Island.