[Sa'ar Chasm]

I'm not positive, but I think that you're referring here to Wotan's theme which recurs throughout the Ring cycle, sometimes called in Act III of this opera

You can hear it in the Kill Da Wabbit short (which is why I thought they were from the same opera) where Bugs is wearing the blonde wig and pointy breastplate, trying to woo Fudd from atop the pudgiest horse I've ever seen.

Other things by Holst besides The Planets (like the two Suites for Military Band, for example)

The first suite (which I played in City Band) got recycled into something called the Hebrides Suite (which I played in high school), by some composer whose name escapes me. The first and fourth movements of the latter were definitely inspired by the Holst piece (you can hear samples here: http://www.ssyo.org/ssyo.org/PERFORMANCE_SAMPLES.htm).