The Star-Spangled Banner is the national anthem of the United States of America. The lyrics come from "Defence of Fort McHenry", a poem written in 1814 by the 35-year-old amateur poet Francis Scott Key after witnessing the bombardment of Fort McHenry by Royal Navy ships in Chesapeake Bay during the Battle of Baltimore in the War of 1812.
The poem was set to the tune of a popular British drinking song, written by John Stafford Smith for the Anacreontic Society, a men's social club in London. "The Anacreontic Song" (or "To Anacreon in Heaven"), set to various lyrics, was already popular in the United States. Set to Key's poem and renamed "The Star-Spangled Banner", it would soon become a well-known American patriotic song. With a range of one and a half octaves, it is known for being difficult to sing. Although the song has four stanzas, only the first is commonly sung today, with the fourth ("O thus be it ever when free men shall stand...") added on more formal occasions.