Answer: Rhetorical Devices:
Rhetorical question in the first four verses of the first stanza: O! say can you see. . . o'er the ramparts we watched were so galantly streaming?, Another rhetorical question question at the end of the stanza: O! say does that star-spangled banner yet wave o'er the land of the free and the home of the brave?
The second and third stanzas lso begin with rhetorical querstions about What is that which the breeze. . .half discloses?
Where is that band. . . that so vauntingly swore. . .shall leave us no more?
All of this sets up a theme: Will the fort hold up? Will the troops inside be able to defend and hold the fort that protects the city-- and symbolically, the country. As long as the flag is flyng, the American troops are holding the fort and have not surrendered.
In those verses there is also a good example of parallel structure (repetition of grammatical pattern): land of the free, home of the brave.
Alliteration: Broad stripes, Bright stars. Rockets Red glare
gloom of the grave (Stanza 3 v. 6)
"Praise the Power" < also figurative language to say "Thank God"
Figurative language: "twilight's last gleaming" to describe dusk.
"star-spangled banner" to describe the flag.
"mists of the deep: to describe fog (stanza 2 v1)
"cause that is just" describes the idea of defending freedom and democracy
"land of the free and the home of the brave" to describe the young United States of America. This is also Repetition: it is the ending of each of the four stanzas, at first as a question, then as an answer and an affirmation that the battle has been won and the flag will continue to fly over the new nation.
"Heaven-rescued land" also refers to the USA.
The third stanza ends with the turning point: The star-spangled banner in triumph doth wave. . )
Explanation: Francis Scott Key is describing the battle in figurative language, to express the emotions of wonder and doubt, then triumph and hope that the nation will endure. The fluttering of the flag is a symbol for the challenges of the battle and the challenges facing the nation.