Campbell was born in
Newcastle,
New South Wales into a working-class family of Scots descent. Campbell along with his brothers John, Geoff, Gregory, Mario and Philip formed an especially close family. Christine Campbell, the wife of Philip "Bull" Campbell, noted that the brothers Campbell were so close that she felt like an outsider with the brothers despite married to a Campbell. "Caesar" Campbell as the oldest of the Campbell brothers served as their leader. An amateur boxer and an illegal bare-knuckle fighter, in 1969, Campbell started the Gladiators Motorcycle Club of
Sydney with his brothers, but then realised a Gladiators already existed up North so he ended his Sydney Gladiators who were not affiliated with the chapter up north. Campbell estimated he was involved in more 800 fights since the age of 14. In 1978, "Caesar" Campbell joined the
Comanchero Motorcycle Club and was again followed by his brothers. In 1980, Campbell was promoted up to serve as the sergeant-at-arms. In the early 1980s, Campbell served as the focal point of opposition to the leadership of
William "Jock" Ross, a man whom Campbell had come to strongly dislike. Campbell resented the para-military training Ross had forced upon the Comancheros while Ross was jealous of Campbell's greater popularity with the younger members of the Comancheros. In July 1983, at a Comanchero meeting, a shouting match between Campbell and Ross broke out and which ended with Campbell storming out followed by 9 other Comancheros including
Anthony Mark "Snodgrass" Spencer. Under pressure from Campbell who complained that the existing Comanchero clubhouse in Granville was too small, Ross was forced to move the clubhouse to
Birchgrove. Campbell, with a couple of his club brothers caught Ross sleeping with the wife of Comanchero, which was a violation of Ross's own rules that he had drawn up. As sergeant-at-arms, Campbell attempted to enforce the Comanchero rules by having a hearing, which Ross avoided by not showing up. Instead, Ross broke the Comancheros up into two chapters with the anti-Ross Comancheros remaining in Birchgrove under the leadership of Spencer while those loyal to him relocated with him to western Sydney. In November 1983, the Birchgrove chapter under Spencer's leadership joined the
Bandidos Motorcycle Club. Campbell became the first sergeant-at-arms of the Australian Bandidos and was regarded as being the dominant force within the club. The split caused much ill-will, and Ross along with the other Comancheros saw Campbell as being the real leader of the Bandidos with Spencer as a puppet leader. Ross focused most of his venom against Campbell instead of Spencer as he sold T-shirts reading "Nail Caesar" along a photograph of Campbell's face with a x crossed against it. On the wall of the new Comanchero clubhouse in
Harris Park, photographs of Campbell were posted along with messages such as "kill Caesar" and "Caesar-dickhead, asshole, fuckwit, kill the turkey, gums, son of Jaws. Snodgrass loves Caesar up the ass!" Campbell who was considerably tougher than Spencer tended to dominate the Bandidos despite being the sergeant-at-arms. ==Milperra Massacre==