by francopoli

An American lawyer and amateur poet, Francis Scott Key, was on a mercy mission for the release of Dr. William Beanes, a prisoner of the British. Key showed the British letters from wounded British officers praising the care they received from Dr. Beanes. The British agreed to release Beanes, but Key and Beanes were forced to stay with the British until the attack on Baltimore was over. Key watched the proceedings from a truce ship in the Patapsco River. On the morning of the 14th, Key saw the American flag waving above Fort McHenry. Inspired, he began jotting down verses on the back of a letter he was carrying. When Key reached Baltimore, his poem, titled "Defense of Fort McHenry," was printed on pamphlets by the Baltimore American.

Yes, our national anthem is based on a drinking song.