This History.com "This Day in History" features the day that Francis Scott Key wrote the poem "The Star-Spangled Banner", after witnessing the shelling of Fort McHenry by the British. This poem may be the longest-lasting consequence of the War of 1812.
"The poem was printed in newspapers and eventually set to the music of a popular English drinking tune called "To Anacreon in Heaven" by composer John Stafford Smith. People began referring to the song as "The Star-Spangled Banner" and in 1916 President Woodrow Wilson announced that it should be played at all official events. It was adopted as the national anthem on March 3, 1931."