The American National Hymn was created by Francis Scott Key who still saw the American Flag waving over Ft. McHenry in the morning hours, "by the dawns early light", after America had won the war of 1812 against the British. He wrote the hymn as a mirror to what he experienced these days, that although the british troops heaviely bombarded the Americans from their ships, victory prevailed for the American side.
Although one can hardly imagine, when seeing the rockets of today, already in 1812 armies fought with solid fuel propelled rockets, in their basics similar to the ones still existing today.