Queen Elizabeth II, who died Thursday after a historic reign as monarch of the United Kingdom, was a steadfast ally of the United States, notably breaking tradition by singing the U.S. national anthem just days after 9/11. The queen joined a crowd of thousands in singing “The Star-Spangled Banner” during a memorial service at St. Paul’s Cathedral in London for the victims on Sept. 14, 2001. Richard Kay, a columnist for the Daily Mail, wrote at the time about how unusual this was for a monarch, saying, “The Queen does not ‘sing’ national anthems. Her mouth never opens when they...