Francis Scott Key wrote his poem after the 1814 attack on Baltimore’s Fort McHenry. Much later it became the national anthem. (Associated Press)

The original handwritten manuscript of “The Star-Spangled Banner” and the flag that inspired the song’s lyrics will be displayed together at the Smithsonian’s National Museum of American History, the first time the historic pieces are believed to have been shown side by side.

The manuscript normally is on display at the Maryland Historical Society in Baltimore, and the flag has been at the Smithsonian since the early 1900s. They can be viewed together from Flag Day, June 14, through July 6. The display is the start of celebrations marking 200 years since the song was written on September 14, 1814.

Francis Scott Key wrote the song’s words during the War of 1812. Key watched as the British bombarded Baltimore’s Fort McHenry. When he saw the fort’s flag flying after the battle, a signal that U.S. troops had withstood the enemy, he was inspired to write a poem originally called “Defence of Fort McHenry.” The poem, set to music and later renamed, became the country’s national anthem in 1931.

Key’s manuscript has two surprises for viewers who know the song. First, Key’s poem has four stanzas, though the first stanza is the only one that’s traditionally sung. Second, Key wrote, “Oh say can you see through the dawn’s early light,” but crossed out “through” and wrote “by.”

Americans might be more familiar with the flag, which gets millions of visitors a year. It was given to the Smithsonian by the family of Major George Armistead, the commander of Fort McHenry and the man who commissioned the banner with 15 stripes and 15 stars, representing the number of states in the Union at the time.

Except for a period during World War II, when it was housed in Virginia for safekeeping, the flag hasn’t traveled outside Washington since coming to the Smithsonian.

Key’s manuscript has traveled only slightly more often since being purchased for the historical society in the 1950s. In 2011, it was taken by armored vehicle, with a police escort, to Annapolis, Maryland’s capital, and to Fort McHenry. And in 2013, the museum took the manuscript to Mount Olivet Cemetery in Frederick, Maryland, where Key is buried.

Burt Kummerow, the president of the Maryland Historical Society, said he hopes this summer’s exhibit will be a chance for people to study the song’s words. He called putting the manuscript and flag together a “very, very special moment.”

“It isn’t going to happen again anytime soon,” he said.

— Associated Press