[2] The gunfight had its roots in the rivalry that developed after a group of Comancheros broke away and formed the first Bandidos Motorcycle Club chapter in Australia.

Those who supported bringing charges against Ross, the six Campbell brothers, the three McElwaine brothers, Anthony "Snodgrass" Spencer (Snoddy) and Charles "Charlie" Sciberras remained at the Birchgrove clubhouse that overlooked Yurulbin Park[4] while Ross and the remaining Comancheros set up a new clubhouse in Harris Park.

Spencer had visited several outlaw clubs in America two years earlier and remembered how much respect U.S. Bandidos showed to him, so he contacted their National President Ronnie Hodge.

Clubhouse attacks and other violence continued until August when Campbell alleged that Spencer and Ross "declared war" in a phone call.

[3] An advertisement for a British motorcycle club swap meet was placed in a few local press releases, to be held at the Viking Tavern, with a scheduled start at 10 am on Sunday, 2 September 1984.

On that day at around 1 pm, 19 armed Comancheros entered the car park of the Viking Tavern during the swap meet and took up positions in hiding.

Using walkie-talkies for communication, Comanchero leader "Jock" Ross, a military enthusiast, intended to stand in the open to give the appearance he was alone, hoping to draw the Bandidos into a pincer movement that was based on the "Bullhorn Ambush" that he read had been used in the Anglo-Zulu War.

[7] The Bandidos pulled up in a group at the western end of the car park and, after distributing guns and other weapons, moved to confront the Comancheros president.

[9] The initial confrontation between the clubs was verbal, involving the brandishing of "non-lethal" weapons and challenges to drop the guns and settle it like men but ended with the accidental discharge of a shotgun into the air.

[12] The by-stander Linda Motton had been reading an Agatha Christie novel in her car while she was hit by shotgun pellets fired by Gregory "Shadow" Campbell who was attempting to kill the Comanchero Glen Eaves.

[15] Motton recalled feeling angry that the bikers had decided to turn the parking lot of the Viking Tavern into a battlefield and used her camera to take photographs of what was happening.

[14] Rather than taking cover, Walters had watched the violence in fasciation..[14] The bullet struck her in the face, severed the lower part of her jaw from the rest of her body and killed her instantly when it severed her spinal cord..[14] Apparently not realising he just killed Walters, Cianter continued to shoot at Kuclear and wounded him.

[19] Despite being outnumbered and taking greater losses, the Comacheroes were able to push the back the Bandidos who retreated behind the Holden lorry of Philip "Bull" Campbell.

[19] At that point, Kucler and Eaves appeared and opened fire on the lorry, wounding Wellington who was struck in the face with broken glass.

[16] The patrons inside the Viking Tavern remained ignorant about what was happening as they watched The Blues Brothers film on the bar's television until the Comanchero Kevork "Kraut" Tomasian, stumbled in with his left arm almost severed into two because of a shotgun blast.

[20] After realising he'd been caught off guard and not having had the chance to set up a formal battle plan, Jock Ross ran from the back of the tavern holding a machete in one hand and a pick handle in the other.

[21][11] Spencer did not take part in the battle and instead cowered in fear inside of his car despite having a gun on him, a decision that led his men to label him a coward.

[22] Police responded after receiving reports that a man had gone berserk with a rifle at the Viking Tavern in Milperra, and that shots had been fired.

The fighting continued for at least 10 minutes while police helicopters circled overhead, with members of the public fleeing to the tavern and nearby properties as soon as the shooting started.

One man who took part in the shoot-out in the Viking Tavern who wished to be anonymous stated in 2014: “Milperra was catastrophic; it was a ridiculous and terrible thing to happen.

"[23] Stephenson dismissed the later claims made by both the Comancheros and Bandidos that no violence was planned for the swap meet as he stated: "I simply can’t accept that.

[28][clarification needed] During the longest joint criminal trial in New South Wales history,[citation needed] 58 policemen provided security, including armed members of the Tactical Operations Unit who were stationed in the courtroom, and witnesses required armed guards from the Witness Security Unit to escort them home.

The following day, it was found that two were ineligible, causing presiding judge Justice Adrian Roden to dismiss all five and order that jury selection begin again.

Commonwealth Games gold medallist boxer Philip "Knuckles" McElwaine was found guilty only of affray; he was the only motorcycle club member to be acquitted of the manslaughter and murder charges that were brought against him.

[32][c] In a repetition of the circumstances that led to the Milperra massacre, in early 2007 more than 60 members of the Parramatta and Granville chapters of the Nomads, previously affiliated with the Comancheros, defected to the Bandidos.

[33] New South Wales Police set up Operation Ranmore to stop the violence escalating, which resulted in 340 people arrested on 883 charges as of January 2008.

[34] In 2002, Australian film maker Martin Brown produced a documentary titled 1% One Percenters Search for a Screenplay in an effort to raise interest for a big budget movie of the massacre.

Colin "Caesar" Campbell has criticised the series for not consulting with those who were there, presenting an incorrect chronology of events and motives, and portraying "lazy stereotypes.