Although Vulgar Display of Power remains Pantera's best and definitive album, Cowboys from Hell was the creative breakthrough that set the stage for its conception.

Not only were its demos responsible for getting Pantera signed to a major label in the first place, but its fresh musical perspective also gave them a much-needed blank slate with which to conquer the 1990s and, first and foremost, erase their 1980s failures.

These failures were cataloged on no less than four independently released LPs packed with largely derivative and thoroughly unimpressive hair metal, and only the fourth of them even counted with recently installed lead vocalist Phil Anselmo, whose broader influences and irrepressible energy cannot be underestimated in altering Pantera's fate.

As the "new guy" entering the Texans' insular world, Anselmo made only tentative contributions to that fourth Pantera album, 1988's Power Metal, but its incremental heaviness and titular statement of intent nevertheless presaged the wholesale reinvention that would be effectively crystallized by Cowboys from Hell.

Here, at last, virtuoso guitarist Diamond (soon to be rechristened Dimebag) Darrell Abbott was finally inspired to snap out of the rampant Van Halen-isms that had creatively shackled his formidable talents thus far, and established his own unmistakable imprint for the instrument, and, by extension, Pantera's signature sound.

This was characterized by a subtlety-free sledgehammer approach informed by, but not beholden to, recent developments in extreme metal, as well as a groove-laden, muscular riffing style punctuated by squealing pinch harmonics -- as illustrated to perfection by the downtuned post-thrash beatdown of the title track, "Primal Concrete Sledge," and "The Art of Shredding," among others.

For his part, Anselmo was only too eager to decorate Darrell's blunt rhythmic onslaught with cavernous roars declaiming impetuous and empowering lyrics that challenged all comers.

In the process, he virtually abandoned his impressive melodic singing range (on par with the great Rob Halford) altogether, only reaching for those higher registers on "Shattered" (a rather misplaced throwback to the power metal era) and the stately lament "Cemetery Gates," which, years later, would sadly serve as requiem for Darrell's untimely passing.

Not to be left out, drummer Vinnie Paul almost matched his baby brother's coming-out party with a heretofore unknown percussive dexterity, and bassist Rex Brown not only managed to keep up with Darrell's six-string tour de force, but bolstered the band's bottom end with added gut-punching power.

So it was that, in what can truly be described as a collective ritual of musical catharsis, the members of Pantera were reborn as Cowboys from Hell, simultaneously defining an entirely new subgenre in the process: groove metal.

[Indeed, such was the album's lasting impact that in time it was accorded a 20th anniversary reissue comprised of three separate discs: the first contained a complete remastering of the original set; the second packed 12 live recordings, of which seven (recorded at the 1990 Foundations Forum music industry event) were previously unreleased; and the third collected the all-important album demos (most of them very faithful to the album versions, although "Shattered" boasts an intro that was later dropped -- "Cemetery Gates" still lacks the intro it got) plus a never-heard album outtake called "The Will to Survive," which, with its more traditional heavy metal riff and predominating melodic vocals from Anselmo, wouldn't have sounded out of place on Judas Priest's Painkiller.].