March 3 is National Anthem Day in the United States!
After seeing the British attack Baltimore Harbor during the War of 1812, lawyer Francis Scott Key was inspired by the American flag that remained waving over Fort McHenry. This sight moved him to write the Star-Spangled Banner.
The song was very popular and was played at formal functions and public events from then on. However, the Star-Spangled Banner did not become the official national anthem of the United States of America until March 3, 1931.