The narrator describes what Francis Scott Key observed: the British bombardment of Fort McHenry in 1814 during the War of 1812. He witnessed Americans standing strong during the night, despite heavy canon fire from the full British fleet. In the morning as the fog lifted, the British were astonished that the American flag remained standing over the rampart. When Key investigated the scene, he found that the flag had suffered continuous hits from the British fleet; yet, the citizenry gave their lives to keep the flag pole up and keep the flag flying high over Fort McHenry.
Americans secured their independence and Francis Scott Key penned the lyrics to our National Anthem from the war scene he witnessed! Key remembered what George Washington had said: "the thing that sets the American Christian apart from all other people in the world is he will die on his feet before he dies on his knees!"
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Video location on UTube: https://www.youtube.com/watch?v=YaxGNQE5ZLA
Good information below the video.
Wikipedia on Francis Scott Key: https://en.wikipedia.org/wiki/Francis_Scott_Key