State holiday in Maryland, US
Defenders Day is a longtime legal holiday on September 12, in the U.S. state of Maryland, in the City of Baltimore and surrounding Baltimore County. It commemorates the successful defense of the city of Baltimore on September 12-13-14, 1814 from an invading British force during the War of 1812, an event which led to the writing of a poem, which when set to music a few days later, became known as "The Star-Spangled Banner", which in 1931 was designated as the national anthem of the United States.