Unbroken, a film Angelina Jolie directed about the plight of an American Olympian turned World War II prisoner, helped her tackle motherhood, the Oscar-winning actress said.

Hundreds of fans crowded outside a Sydney theatre to welcome Jolie to Australia for the world premiere of her second directng effort.

Based on a bestselling book by Laura Hillenbrand, the film tells how Louis Zamperini, an Olympic sprinter, spent 47 days on a life raft after his plane crashed into the Pacific, and was then held for two years by the Japanese.

“I think as a human being, as a mother, as someone who works internationally, I needed desperately to know a man like Louis Zamperini in my life, to know that there is hope,” Jolie said.

The strength of a strong heart and an indomitable will is valuable and it’s worth something

She was able to show Zamperini an early cut of the film, shot in Australia, before his death in July, aged 97.

“The strength of a strong heart and an indomitable will is valuable and it’s worth something,” she added.

“We have to remember that and hold onto that because that’s what will pull us through and it’s what has always pulled people through dark times.”

Jolie was joined on the red carpet by her husband, actor Brad Pitt, and Jack O’Connell, who plays Zamperini.

The mother of six told Vanity Fair magazine this month she was open to pursuing a life in politics, or public service.

Jolie’s first film as a director, In the Land of Blood and Honey, was set during the Bosnian war and released in 2011. She recently finished filming By the Sea in Gozo.