Happy Birthday ‘Star Spangled Banner’

15 star US flag / AP

Francis Scott Key penned the U.S. National Anthem as he watched the Battle of Baltimore on this day in 1814.

Key, an attorney by day, was onboard the British HMS Tonnant to negotiate the release of several American prisoners. Plans changed, however when a major battle in the War of 1812 broke out. A few miles away from the Tonnant, the British troops began bombing Fort McHenry in an effort to capture the port city of Baltimore.

The bombardment started Sept. 13, in the middle of a thunderstorm, and lasted 25 hours.  Amidst the bombs and canon fire, the American troops at Fort McHenry took down their weatherbeaten 15-star flag and replaced it with their larger, ceremonial flag as a show of strength against the king's forces.

Key witnessed this symbolic act from the Tonnant and began writing the "The Defence [sic] of Fort McHenry" to accompany a famous melody called "To Anacreon in Heaven."

The Americans fended off the British; Key then published his poem in a local paper on Sept. 20, 1814. The poem and tune became a celebrated victory cry for the country.

Congress officially made it the National Anthem in 1931.