From Publius:
As a classical musician, I have some information about the musical side of the piece that might be useful for your thread.
The song began its existence as the opening anthem for the ceremonies of London’s Anachreotic Society in the 1750's. It was titled "To Anachreon in Heaven" and consisted of twelve verses of a debate between Anachreon and Bacchus over the benefits of alcohol. This was fitting because the Anachreotic Society was a gentleman’s drinking club, one of many gentlemen’s societies that dotted the London social scene in the second half of the 18th Century. (There were other societies such the Wig Club and the Hellfire Society that we don’t discuss in the presence of the fairer sex.)
The song was arranged for mixed strings and continuo (harpsichord and cello as rhythm instruments) with a choral complement of two tenor lines and two baritone or bass lines. (In choral-speak it is designated TTBB.) The accidentals (sharps and flats) did not exist in the original melody, nor were there the dotted notes (syncopations) that we’re used to hearing. In its original arrangement in 3/4 minuet time, it sounds like something George Frederick Handel would have written on a bad day. (Some scores attribute the melody to Sidney Smith, but that is incorrect. Smith was an arranger whose gift was writing piano reductions of opera tunes. His only contribution here was to write one of many piano arrangements of the Star Spangled Banner.)
The song came to America without its gentility. It became a favorite anthem of tavern drunks but with different, more vulgar words. In shedding its choral arrangement and becoming a tavern song, a single vocal line was distilled from bits of the tenor and baritone lines, so that the song now began deep in the bass register and ended up several octaves higher in the tenor register. While this made it difficult to impossible for sober people to sing, drunks had no trouble with it.
By a stroke of luck, Francis Scott Key’s poem fit the old song whose melody everybody knew. Thus a new patriotic song was born. In 1931 Congress officially made it the national anthem.
Most wind band arrangements are in B-flat. Vocal arrangements are in the key that permits the singer to do a reasonable job. The best known piano arrangement is in C and was written around 1905 by the piano virtuoso Josef Hoffmann who used it to open his concerts. (When played well, it sounds like there are two pianos playing.)
LOL That's our Publius! (Thank you ;)
Back during the Bicentennial, a choral group recorded "Anachreon" in its original TTBB/string orchestra-continuo arrangement. After 12 verses it gets to be a bit much, but you can hear the original tune minus all the changes that occurred before it crossed the Atlantic.