“The Pledge of Allegiance Tour”—it sounds like a campaign for patriotism in the wake of the Sept. 11 attacks, featuring country singers or aging pop stars. Cut out the pop, add some violence and obscenity, keep some of the political impact and the shot is closer to the mark. The tour is a celebration that uses anger, angst and passion to create a kind of energy one cannot find tapping a foot and smoking a joint at a Dave Matthews Band show. The most significant metal excursion of the post-summer season, the Pledge of Allegiance tour made its way to Worcester on Oct. 30 and left concertgoers bruised, sweaty, bloody and happy.

The “allegiance” declared by these fans is to the bands that give them an outlet where they can vent their frustrations, which manifest themselves either in the form of mosh pit violence or stadium screaming. The Worcester Centrum was not a place for the meek this past Tuesday night, as two of the most popular acts in heavy metal brought out many of the skinheaded/long-haired, tattooed, pierced, goateed, leather loving, adrenaline-hunting denizens of the greater New England area. System of a Down and Slipknot shared the headlining slot on the ticket, but with their unrivaled stage-show it was Slipknot who finished the night. A collection of nine Iowans in matching full-body factory suits and unique psycho-Satanic rubber masks, Slipknot were the main attraction for the thousands in attendance. The group’s second album, Iowa, was recently released and has catapulted the crew to the top of the nu-metal ranks.

Nu-metal is the moniker for today’s second generation of metal stars who were raised on 80s mainstays like Slayer, Anthrax and Metallica (although not so much their last two albums), and have blended those influences with slices of hip-hop and hardcore: Korn, Linkin Park, POD and Limp Bizkit serve as the most commercial (and hence recognizable and successful) of this crew. Both System and Slipknot have carved a niche for themselves in this emerging genre.

System of a Down are comprised of four Californian Armenian-Americans who have come to use their music as a means for disseminating their political ideals, replacing Rage Against the Machine as metal’s prominent political activists. Some areas of concern for the four-piece band, consisting of singer Serj Tankian, guitarist Daron Malakian, bassist Shavo Odadjian and drummer John Dolomayan, include an aversion for American cultural and political hegemony, a desire for global recognition of and reparations for the Armenian genocide by Turkey, and a suspicion for virtually all aspects of the American political system. Their track “Prison Song” makes the claim that the mandatory minimum sentencing for drug offenders has been proven ineffective in deterring crime and should be abolished, in addition to demanding an overall decrease in the number of law enforcement agents. The lyrics also quote statistics claiming that the American prison population has doubled since 1985, leading Tankian to conclude that the American government is “trying to build a prison for you and me to live in.”

Whether one agrees with System’s political views, it’s certain that a great many are listening to what the band have to say. Their sophomore opus, Toxicity, has spawned the band’s first true hit, “Chop Suey.” The track’s music video has gained surprising attention on MTV as frequent play on mainstream radio. But while the success of other metal acts has been tainted with inner-industry cries of “sell-out” and a subsequent loss of respect in the metal community, System have not changed their sound to sell records, but have instead found a growing appreciation from the public. System’s sound is atypical in that their melodies can be at once punishing and low and then sweet and elegant. Tankian’s voice matches the flexibility of the guitar as he stretches his vocal range from a hellish roar to the floating timbre of a classic tenor.

Their stage show was most impressive in that their sound was not muddled and bland—too often metal acts cannot bring the crispness of a album’s track to their live performance. Their lyrical activism was matched at one point by a personal act of activism by Malakin on behalf of women’s rights. Before their final song, Malakin addressed a large male fan in the front of the mosh pit (who was being escorted out of the area for punching a girl in view of security) saying, “I wish you weren’t so fat…I bet you wish you weren’t so fat, too. Maybe then you wouldn’t push girls around, huh?” All in all, System were successful in both entertaining the crowd and expounding their political messages, but the fans were much more anxious to witness the mayhem that was the Slipknot stage show—the most unique and electrifying in metal today.

Not a traditional four or five piece band, Slipknot are a nine-man unit comprised of two guitarists, one drummer, two “custom percussionists” (who bash kegs, tin drums and each other at various points), a bassist, a DJ, a sampler and a vocalist. The result of this strange amalgamation of participants is that one moment the guitars are muted and pulsing, vocals slickly rapped over with a mild hip-hop scratching, and the next a double bass drum is rumbling, the guitars are screeching, and the lead vocalist is screaming as if his lungs were on fire.

While Iowa is less hip-hop flavored than the band’s self-titled debut, it still has a more rhythmic and groove-oriented hook than the works of current metal purists like Pantera or Nevermore. The album combines traditional metal structure with moments of hip-hop bounce, and stirs them with a healthy dose of death metal precision and hardcore aggression.

The band’s message is one of violent individualism, a sentiment that was hammered home on Tuesday in the chorus of the band’s opening track, “People=Shit,” which saw the entire crowd exploding forth with the title again and again as band members screamed, jumped and pummeled each other, setting the stage for crowd’s insanity with their own. The lyrical content of Slipknot’s music is, at alternating points, poetic, enigmatic and even disturbing. Several lines from “Disasterpiece” illustrate the combination of these elements: “I want to slit your throat and fuck the wound / I want to push myself in and feel the swoon… I am infinite, I am the infant finite / Come a little closer and I’ll show you why / No one is safe!”

Categorically anti-commercial in their tone, Slipknot ignored the typical formula used by metal bands searching for success: produce one radio-friendly song, often an 80s cover to get exposure, enjoy reasonable sales of the debut album, then soften the vocals, drop some distortion and get yourself onto TRL with album two (witness the mass popularity of Limp Bizkit’s George Michael cover “Faith,” followed by the huge success of “Nookie,” mirrored closely by Orgy’s mainstream success with the New Order cover “Blue Monday”). Instead, Slipknot abandoned much of the commercial appeal of their first album, namely their hip-hop base, and instead embraced the more esoteric elements of death metal and hardcore—double-bass drumming, over-the-top shredding guitar, and grinding vocals.

Slipknot’s newest single, “Heretic Anthem,” illustrates their commitment to rejecting the saccharine sweat world of commercial success: “I’m a pop star threat and I’m not dead yet… It’s evilsonic, it’s pornaholic / Breakdowns, obscenities, it’s all I wanna be / If you’re 555 then I’m 666!” The band are not Satanic, yet they use Satanic imagery as a means to express their rejection of mainstream society. In fact, as the stage was being set for the Iowans, a huge black flag hid the area, emblazoned with the band’s tribal “S” logo entwined with a red pentagram. Slipknot’s overall nihilistic message fits with their onstage personas, that of anonymous and inhuman characters/monsters. With their faces covered by demonic masks, their identities are marked only by the numbers on their sleeves: “0” through “8.”

Their hour-long set of crowd-chanting, mosh-pitting anthems was punctuated by three notable moments. The first was a series of solos—initially, DJ Sid “#0” (who wears a gas-mask), a turntable master, scratched and spun in an ever-quickening crescendo as strobe lights flickered; the second spotlighted the drummer—the kabuki-masked musician drummed at a hellish pace while his drum set floated upside down and rotated above the stage. Slipknot’s second highlight was their final track, “Surfacing,” a song which they claim is the “new national anthem” for their fans (whom they’ve affectionately dubbed “the maggots”). The track found the near-capacity Centrum crowd screaming in unison, from the front of the pit to the upperdeck seats, “Fuck you all / Fuck this world / Fuck everything that you stand for / Don’t belong / Don’t exist / Don’t give a shit / Don’t ever judge me!” This anthem settles the message behind Slipknot’s madness—a violently-guarded individuality coupled with a rejection of conformity.

The final highlight was a turn of politicization that one might not have expected from Slipknot. In between tracks at one point, the drummer held up an American flag while the vocalist, “#8,” gave a small speech calling for an end to hate crimes against Muslims and Arab-Americans, acts he described as “fucking bullshit.” He called for all Americans to accept differences in race and creed, “And know that we will punish the guilty and not the innocent!”

This moment of political attention illustrates some of metal’s new relevance. No longer relegated solely to college radio or late-night music television, metal has become a notable part of our youth culture—expressing both the eternal youthful rejection of authority found in 50s rock and 60s punk in addition to greater global concerns.

Twenty-first century metal, championed in different fashions by both System of a Down and Slipknot, offers more than the hedonistic hair bands or Satanic ritualists of the 80s—it’s louder, it’s angrier and, more importantly, it’s often smarter.