Francis Scott Key wrote "The Star-Spangled Banner" during the War of 1812, specifically inspired by the defense of Fort McHenry in Baltimore Harbor. On September 13-14, 1814, Key, who was a lawyer and amateur poet, was aboard a British ship to negotiate the release of a friend who had been captured. While he was there, he witnessed the intense bombardment of Fort McHenry by British forces.
As dawn broke on September 14, Key saw the American flag—referred to as the "star-spangled banner"—still flying over the fort, signifying that the American defenders had withstood the attack. Moved by this sight and the resilience of the American forces, Key wrote a poem entitled "Defence of Fort M'Henry," which later became known as "The Star-Spangled Banner." The poem was set to the music of a popular British song and eventually became the national anthem of the United States.