Question: What shape was the bastion fort whose defense inspired the poem that the American national anthem was based on?
Sentence (from "The Star-Spangled Banner"): The lyrics come from "Defence of Fort M'Henry", a poem written on September 14, 1814, by the 35-year-old lawyer and amateur poet Francis Scott Key after witnessing the bombardment of Fort McHenry by British ships of the Royal Navy in Baltimore Harbor during the Battle of Baltimore in the War of 1812.
Relevant evidence: Yes