Names can be pretty exciting things for composers. If you've got the right combination of letters in your name, you can encode it into music, leaving a kind of musical signature in your works to mark them as your own. The most famous of these is undoubtedly that of Johann Sebastian Bach, whose last name, using the German system of note nomenclature, translates directly into the notes B-flat, A, C, B-natural. Bach himself used that motif in numerous pieces (iconically, it's the last subject in the last, unfinished, fugue in The Art of Fugue (5'33" in this recording, tho the whole cycle is worth a listen)), and, Bach enjoying the status that he does in the musical landscape, numerous other composers have deployed it in their works as a kind of homage, some more subtly than others.
Exhibit A for unsubtle uses could well go to today's piece, Ron Nelson's Passacaglia, helpfully subtitled Homage on B-A-C-H. Written in 1992, it made wind band history by winning all three of the major awards in wind band composition in the 1993-4 season, and has quickly become a staple of the repertoire. Nelson was born in 1929 in Joliet, Illinois, but felt stifled by small-town life and decamped to California before bouncing to the other side of the country to study at Eastman for his Bachelor's, Master's, and Doctorate degrees. He subsequently earned a Fulbright to study in Paris, but opted to work with Arthur Honegger instead of Nadia Boulanger, making him one of the few composers to study in Paris in the 50s who didn't train with her. (Honegger, unfortunately, died in November of that year, so Nelson wound up studying with a student of Richard Strauss, Tony Aubin instead.) On his return to the States, Nelson took a position at Brown University, where he taught until his retirement in 1993. He currently lives in Arizona, and may well still be writing music.
Like many composers, Nelson was drawn to the orchestra as the high-prestige ensemble of choice (he says he was never very good at chamber music), but found the conservatism of their programming and audiences off-putting, especially next to the eager hunger for new works in the wind band world. I find it illuminating to look at his comments on the differences between the genres, as he grew up largely before Frederick Fennell revolutionized the wind band landscape with the Eastman Wind Ensemble from the 50s on. Nelson grew up in an age of orchestral transcriptions drowning in a sea of clarinets, and claims to think of his music as not having that classic wind band sound; I grew up when the genre was in a rather different place, and think of Nelson having exactly the classic wind band sound. Genre shifts are weird.
So many terms in music have nice theoretical definitions that are often blatantly ignored in practice, and "passacaglia" is firmly in this camp. The basic idea is that it's a set of variations over a repeating bassline, but it frequently gets conflated with a "chaconne", which is, strictly speaking, a set of variations over a repeating chord progression. Composers caring more about writing good music than labeling everything perfectly, the two are often used interchangeably, and sometimes on pieces that are a far cry from either definition. Fortunately for the theory-concerned, Nelson's Passacaglia is, in fact, a passacaglia, and a pretty classic one at that, with an eight-measure bassline that's repeated twenty-five times over the course of the work.
Ominous low rumblings start the music out, with muted brass muttering the BACH motif several times before the first clear statement of the passacaglia theme, about 40 seconds in. Some passacaglias have a fragmented, segmented feel, with a cadence every eight bars or so, but Nelson is careful to make his form organic and smooth, so the divisions between repetitions blur and shimmer in his strained twilight world. Other voices sneak into the texture gradually, adding layers of contrapuntal activity, freely sliding around like shifting mists obscuring the view on a winding path, the BACH motive echoing like the calls of a distant, unseen bird.
Nearly halfway thru, a solo alto saxophone has a clear statement of the theme, floating out delicately above the morass, and this leads to a rather jazzy cadence that seems to trigger something deep in the heart of the music, sending woodwinds scurrying off in increasing flurries of activity and letting the percussion come increasingly to the fore. Some extensive hocketing ensues before the snare drum, bass drum, and cymbals settle into a tight groove, which gives new life to the BACH motive. From there, it's one slow build to the end, where the nattering chromaticism is swept away with an earth-shattering blaze of brassy confidence and glory.