Answer: Attorney
On September 13, 1814, Key was on a British ship as Fort McHenry in Baltimore harbor, was bombarded by the attacking British. Key was negotiating a prisoner exchange with the British forces. When the day dawned, he saw the flag flying above the fort and was inspired to write the lines that later became the National Anthem. You can get the complete story in this video blog a Don’t Know Much About® Field Trip.
Francis Scott Key was born on August 1, 1779, in western Maryland. His family was very wealthy and owned an estate called “Terra Rubra.” When Francis was 10 years old, his parents sent him to grammar school in Annapolis. After graduating at the age of 17, he began to study law in Annapolis while working with his uncle’s law firm. By 1805, he had a well-established law practice of his own in Georgetown, a surburb of Washington, D.C. By 1814, he had appeared many times before the Supreme Court, and had been appointed the United States District Attorney.
Source: National Park Service/Fort McHenry National Monument and Historic Shrine