Defenders Day is a legal holiday in the U.S. state of Maryland^[1] It commemorates the successful defense of the city of Baltimore on September 12, 1814 from an invading British force during the War of 1812, an event which would lead to the writing of "The Star-Spangled Banner" as the national anthem of the United States.

In 1814, following the burning of Washington, a British force commanded by Major General Robert Ross landed north of Baltimore and began an advance on the city. He was met almost immediately by a detachment from the Baltimore garrison led by American General John Stricker, commencing the Battle of North Point. The resulting halt of the larger British force allowed Baltimore to organize its defenses against a later attempted naval invasion. It was during this conflict, the Battle of Baltimore, that Fort McHenry was shelled by the British but refused to surrender, and an inspired Maryland lawyer named Francis Scott Key composed the words to what would later become "The Star-Spangled Banner", eventually proclaimed the national anthem of the United States.