Julian and the Cobleighs held a deep-rooted rivalry with Edward Kenway, a young Welshman. In the summer of 1711, Julian, Tom, and Seth Cobleigh had a fight outside the Auld Shillelagh tavern in Bristol with Edward, who was trying to defend a drunken woman called Rose from being abused sexually by Tom. Despite quickly gaining the upper hand, the trio were stopped by Rose's employer, Caroline Scott. Two days later, the group slaughtered two of the Kenways' sheep and placed the carcasses in front of the Kenway house in order to scare Edward, who reacted badly to the provocation. Edward's father refused to let him retaliate, explaining that Julian and his associates and many merchants of Bristol had joined the Trade Organisation, an association of tradesmen protected by "powerful men".
The rivalry between the Cobleighs and Edward reached a head when Julian and Tom became involved in a plot to kill or otherwise remove Edward from the area. In late 1712, Julian, Tom, and the Templar Wilson burned down the Kenway farmstead while Edward's parents were sleeping inside. Having returned from Bristol, Edward tried to stop them, but the group pinned him to the ground and knocked him unconscious before leaving.
After having alerted his parents, an infuriated Edward returned to the Auld Shillelagh, searching for the group. Taking a sword from the wall, he awaited the arrival of Julian, Tom, and Seth. Once the trio stepped into the tavern, Edward ran Julian through with the sword, killing him before chasing after the Cobleighs.