Thrash's takeover of heavy metal wasn't complete in the mid-1980s, but its dominance and influence on the genre can be traced to the events of one triumphant and tragic year: 1986.

An aggressive collision of punk rock energy with a generation's worth of hard rock riffs, thrash metal had already been peeling the paint off underground rock clubs in San Francisco, Los Angeles and New York for a few years when the powder keg exploded with a trio of albums that laid the template for the next decade-plus of metal: Metallica's Master of Puppets, Megadeth's Peace Sells … but Who's Buying?, and Slayer's Reign in Blood.

"Eighty-six is kind of like [the] tipping point for thrash," says Albert Mudrian, founder and editor in chief of Decibel magazine. "I recognize '86 as the crowning year for that style, but at the same time, just the beginning of the end in a way."

By 1986, the classic thrash metal bands had fully formed identities reflected in the albums they released that year. In Rolling Stone's 100 Greatest Metal Albums of All Time, published in 2017, Peace Sells … but Who's Buying? ranked No. 8; Reign in Blood was No. 6; and Master of Puppets was No. 2. Anthrax's Among the Living, which came out in March of the following year, wasn't far behind at No. 20.

The Big Four of Thrash, as a journalist dubbed them in the '80s, were also charting on the Billboard Top 200, with Master of Puppets, the most successful thrash album from the class of '86, reaching the top 30 and eventually earning six-times platinum sales. While their contemporaries hung out on the chart's lower rungs, Megadeth's Peace Sells … but Who's Buying? would reach platinum, and the albums from Slayer and Anthrax were both certified Gold for half a million albums shipped.

Only a year earlier, record label bidding wars were heating up in the thrash metal scene. Metallica were the first band to sign with a major label, joining the Elektra Records roster in 1984. "Things were brewing — you could tell thrash metal was the next thing up to bat," says founding Megadeth bassist David Ellefson. "Mötley Crüe, Ratt, Quiet Riot, WASP, [all] the Sunset Strip bands were already enjoying their heyday, and our generation was the next thing to come up the ranks."

Michael Alago, the Elektra rep who signed Metallica, set his sights on signing Megadeth next. During a whirlwind week in New York, he took Ellefson and frontman Dave Mustaine to see Metallica open for Ozzy Osbourne at the Meadowlands and whisked them to clubs like CBGB and the Limelight. Megadeth signed with Capitol Records for Peace Sells … but Who's Buying?, but Metallica had paved the way for the thrash signing blitz.

"Metallica's trajectory was so huge. They carved such a wide path for all of us," Ellefson says. "And they were the model: independent to major label, land a huge, major tour like they did with Ozzy, play the arenas."

Released in March 1986, Master of Puppets put Metallica on a much larger stage than their first two albums, Kill 'Em All and Ride the Lightning. As Mudrian says, the band was "a fully formed machine" by then, a tight and relentless juggernaut that moved easily from neck-breaking headbangers like "Battery" and "Damage, Inc." to the epic, anthemic title track and the progressive instrumental "Orion." "It's insane," Mudrian says. "The pace of their evolution was just faster."

Metallica wasn't playing all the typical industry games at the time, though. They weren't on radio or television — they wouldn't even put out a promotional video for MTV until "One," the breakthrough single from 1988's … And Justice For All that introduced them to mainstream success. But the opening slot on the Ozzy tour was about as plum a gig as an up-and-coming metal band could land.

"The fact that Metallica got that slot on the Ozzy tour in early '86, that definitely exposed this new music to a massive mainstream audience," says Scott Ian of Anthrax. "Playing arenas with Ozzy [wasn't] so much the passing of the torch, but it's, 'Hey everyone, check this out, look how cool this is.'"

"There was a mystique around them because they didn't have videos," Mudrian says. "Everybody kind of knew that they were essentially the biggest band out of that group of bands, but it felt like they were kind of operating on their own plane."

Megadeth, meanwhile, had an ace to play that would set them apart from the pack: the mid-tempo, politically charged "Peace Sells," which had been going over well with fans at shows before the band recorded it. The song came together in the band's south-central Los Angeles rehearsal space, where Ellefson and Mustaine slept most nights when they couldn't find anywhere else to crash. Mustaine worked out the opening bass line and showed it to Ellefson, and the band finished the song in two hours at rehearsal that night.

Ian remembers thinking "Peace Sells" was unlike anything the Big Four bands had released to that point. "I was definitely jealous of that track," he recalls. "And what a lyric! I mean, just the whole concept — 'Peace sells, but who's buying' — it's so smart. We were a bunch of f*cking kids, and Mustaine came up with that when he was, what, 22? He's not just writing about axes and cleavers and the devil and Satan and blood. He came up with something super smart in that song, and what a hook."

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MTV agreed. Not only did the video for "Peace Sells" enter rotation (albeit late at night), but the network also cribbed the opening bass lick for the theme music to their MTV News spots. "I remember we had the TV on in the background and [lead guitarist] Chris Poland was doing the dishes," Ellefson says. "And out of nowhere they said, 'MTV News' [hums bassline]. And Chris goes, 'Holy sh*t, was that our song?' And I go, 'F*ck, I think it was!' We started to hear it more and more, and eventually that 'Peace Sells' bass intro became synonymous with MTV News."

By the spring of '86, Slayer had wrapped sessions for its third album, the brutal Reign in Blood, at Hit City West in mid-city LA with their new producer and label head, Rick Rubin of Def Jam Records. In his first rock production role, Rubin established the template he would use to reinvent artists like The Cult and Danzig: straightforward arrangements and bone-dry production.

"We really didn't know to what extent the impact was going to be," says drummer Dave Lombardo. "We were just doing what we loved and recording the songs that we were creating, and Rick Rubin was helping us mold this music in a direction that we weren't really accustomed to. I believe that Rick was really good at trimming the fat in music. Whatever's not necessary, it shouldn't be there."

Rubin's work didn't compromise Slayer's intensity; if anything, he sharpened the band's attack. His influence resulted in shorter songs and a total runtime under 30 minutes, meaning the entire album fit on one side of a cassette. They simply repeated the entire 10-track set on side B. Only two songs — the opener "Angel of Death" and closer "Raining Blood" — exceed four minutes in length, and the shortest, "Necrophobic," is barely a minute and a half long.

"Hell Awaits [1985] was such a statement because it really was at the furthest boundaries of extreme in metal at the time," Ian says. "I remember one of my initial reactions to [Reign in Blood] after listening to it all the way through, I'm like, 'Where's side two?' Of course I f*cking loved it, but I thought there was going to be another 20 minutes of it."

Slayer is fortunate it was released at all. Columbia Records, Def Jam's distribution partner, refused to ship it after hearing "Angel of Death," a song about the crimes of infamous Nazi doctor Josef Mengele. After a six-month delay, Geffen Records stepped in to distribute the album. The band later celebrated Reign in Blood on tour in 2004 with full-album performances culminating in the band being drenched in fake blood that rained from the lighting rig during "Raining Blood."

After Metallica completed their dates with Ozzy, they headed to Europe with Anthrax and Metal Church for the next leg of the Damage, Inc. Tour. Although Anthrax was technically touring their Island Records debut Spreading the Disease, soon-to-be-classics from Among the Living such as "I Am the Law" and "Caught in a Mosh" were popping up in their sets.

"We knew when we were just playing them as a band in our room that we had stepped into a really, really big pile of sh*t because of how excited we were playing those songs and just knowing how the crowd would react," Ian says. "Once we put those in front of a crowd … we were right. We had something special."

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The tour wound through the British Isles and then crossed over to the Scandinavian Peninsula for three shows before hitting mainland Europe. But they never made it past Stockholm, Sweden. On the morning of September 27, just before 7 a.m., their tour bus skidded off the road, killing Cliff Burton, the Metallica bassist who helped steer the band into the adventurous melodies and textures of songs like "Orion." The tour, at least for the moment, was done.

"We all went home [but] I went straight to San Francisco," Ian says. "I was actually staying with James [Hetfield, Metallica singer/guitarist] in his little apartment. Every day we would go out to Kirk [Hammett, Metallica lead guitarist]'s house. He was still living with his mom in the East Bay and we would just hang out and drink beer and shoot the sh*t and talk. They were able to just hang out and tell stories and move forward."

Within a couple of months, Metallica was ready to plug in again. They recruited Flotsam and Jetsam bassist Jason Newstead and returned to the road, where they would stay through 1987. Megadeth would, too, after hooking up with Alice Cooper, who was newly sober and back to playing arenas in support of Constrictor. Anthrax finished tracking Among the Living prior to resuming the Metallica tour. And Slayer teamed up with NYC thrash band Overkill for a U.S. tour of their own.

Metal was quickly evolving due to the influence of thrash. Slayer's lineage led straight to death metal, which began popping up in '87 and '88 and continued to push the genre to new extremes. The influence of Megadeth, Mudrian argues, skipped a generation but surfaced in a big way with metalcore bands in the 2000s. Metallica, of course, went on to recreate hard rock in its image with 1991's Black album, which sold more than 30 million copies worldwide and gave them the widest influence of all the thrash bands.

The Big Four finally appeared on the same bill together in 2010 in a series of concerts in Europe and the US. Any lingering animosities and jealousies were laid to rest — Mustaine, who Metallica fired before recording Kill 'Em All, jammed onstage with his former bandmates, and the bands gave their legions of fans the concert bill they always wanted to see.

"Thrash metal was always this counterculture style of metal, and it has survived strictly on the merit of our fans," Ellefson says. "As much as we've all gone to the Grammys and we've got multiple platinum albums and we've done these big tours, the real success is that our fans made us who we are. And even when mainstream media came and went, the fans kept us alive.

"I think that's telling for the staying power of our genre," he adds. "As I look at the Big Four plaque on my wall with 85,000 fans in Sofia, Bulgaria in 2010 — that wasn't [due to] one or two hit records and a smash on MTV. That's not, like, just a bunch of really great numbers on Spotify. That's a groundswell of, at that time, 30 years of growing something."

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