Question: What shape was the bastion fort whose defense inspired the poem that the American national anthem was based on?
Sentence (from "Fort McHenry"): Fort McHenry, in Baltimore, Maryland, is a historical American coastal pentagonal bastion fort best known for its role in the War of 1812, when it successfully defended Baltimore Harbor from an attack by the British navy from the Chesapeake Bay September 13–14, 1814.
Relevant evidence: Yes