My thanks to fellow Beatles and Star Wars fan Matt Blick, of The Beatles Songwriting Academy, for pointing out a similarity between John Williams' "Rebel Motif" as heard in Star Wars: A New Hope and Leighton Lucas' score to the 1958 movie Ice Cold in Alex. A clip from the latter may be found below.

This music bear striking similarities to Williams', particularly towards the end, around 1:40 - a transcription of which is provided below.

Now compare with the opening scene from A New Hope, as heard at the beginning of the third track from the soundtrack.

Although Alex is fast (a tempo of roughly 180 bpm) and Star Wars is slower (about half as fast), both feature a Mars-inspired ostinato in the lower strings, with a fanfare consisting of two major chords a minor third apart heard in the treble voices. Furthermore, in both, this fanfare opens with a very short anacrusis (think of the "ta" in "ta-da") followed by a long held chord that resolves to the lower chord, which is shorter in duration than the held chord, but longer in duration than the anacrusis.

I think it's a safe bet that Ice Cold in Alex was on John Williams' temp track for Star Wars!

The imperial attack immediately following the open scroll of "A New Hope" uses a chord that is note-for-note identical with the coda of "Mars" from Gustav Holst's The Planets. First, the Star Wars excerpt, lasting from 1:41-1:56 of the following clip:

Now compare that with 6:56-7:11 from "Mars":

For visual reference, here are the two score excerpts side-by-side:

Both pieces use the exact same dissonant chord: A-flat, D-flat, G from bottom to top, with a C in the bass. In Star Wars, for the last few measures Williams adds a C above the dissonant chord as well to keep the chord building in intensity.

Just as the Star Wars main theme shares similarities with the King's Row main theme, so too there are additional themes and motifs used in Star Wars that also bear similarities to historical predecessors. In this case, here is a comparison of the Imperial motif (not to be confused with the famous Imperial March that does not appear until "The Empire Strikes Back") with an excerpt of "Mars" from The Planets by Gustav Holst.