When World War II started in 1939, officials wanted to move the royal family, especially the children, to Canada.
Officials thought it would be safer for them there, away from the bombings.
But the royals refused to be evacuated.
They stayed at Windsor Castle and sheltered in the dungeons during bombing raids.
They hid there with the crown jewels which were wrapped in newspaper to keep them safe.
When the war was over, the Princess and her family celebrated with crowds outside Buckingham Palace.