Many history buffs can explain how “The Star-Spangled Banner” was penned by Francis Scott Key after he witnessed the failed British bombardment of Baltimore’s Fort McHenry in 1814, and some may also know that the song became the U.S. national anthem in 1931. Lesser known are the details of the 117-year journey that shepherded its transformation from inspired poem to officially sanctioned emblem of American patriotism. Originally printed under the title “Defence of Fort M’Henry” and set to the then-popular melody of “The Anacreontic Song,” “The Star-Spangled Banner,” as it later became known, quickly struck a chord among the citizens...