- "You make sure you do take his cock and balls before you finish him. You make that bastard suffer."
- ―Holden to Jenny Kenway, regarding her desire to kill Reginald Birch, 1757.[src]
In his youth, Holden served in the British Army under Edward Braddock during his campaigns in the Dutch Republic, including the Siege of Bergen op Zoom. His brother had been executed alongside the same gallows as Haytham Kenway, who had managed to escape. To avenge his lost kin, Jim aided Haytham in his investigations to find Tom Smith, who allegedly had connections to the murder of Edward Kenway, following which the pair became close friends shortly afterwards.
From there, Haytham invited Holden to London to aid him in his investigations, under the guise of his "gentleman's gentleman"; this included Holden's presence nearby the Theatre Royal on Haytham's mission to assassinate a patron of the Assassin Order. After suspecting the treachery of Reginald Birch, Holden quickly became the only ally Haytham could trust with such sensitive information regarding both his father's murder and the disappearance of Jenny Kenway.
Following Haytham's failed attempt to enter the precursor site in Colonial America, Holden aided the Templar in rescuing his sister, Jenny. Around 1757, while Haytham grew the Templars' influence in the American colonies, Holden had privately tracked Jenny to the Qasr al-Azm, a Damascan palace, where she had initially served as a concubine to the Ottoman court at Topkapı Palace, before being transferred as a servant due to her increasing age.
On Haytham hearing of Holden's discovery, both he and Holden infiltrated the palace to locate Jenny, under the guise of eunuchs. However, upon being discovered, Holden stubbornly chose to stay behind to defend Haytham and Jenny as they made their escape. As a result of this act, Jim was eventually overwhelmed and sent to the Abou Gerbe monastery on Mount Ghebel Eter, Egypt, to undergo operations to become a eunuch.
In September 1757, Haytham tracked down Holden, but greatly suspected that he had already been castrated. Proven true, and on seeing Jim suffering from dehydration – as a result of being buried to his neck in the desert sand – Haytham burned down the monastery and killed many of the priests who conducted the operations on other men in a seething fury, before carrying his weakened friend to safety. After this, Haytham located a cottage where Jenny and Holden could be safe, and the two Kenways gradually nursed Holden of his injuries, though the process took several weeks.
In October, Holden aided Haytham and Jenny on an assault on Reginald Birch's chateau in France, after Haytham had concretely confirmed Birch's orchestration of the raid on his home in Queen Anne's Square during 1735. On Birch's death, Holden helped the prisoners, Monica and Lucio, escape. Despite this, as Haytham attempted to apologize for the conditions in which his fellow Templars had put them through, he was unforgivingly stabbed in the torso by Lucio, who he had captured for Birch in 1753.
As a result of this sudden attack, Holden and Jenny cared for Haytham in Birch's chateau during his recovery over the coming months. Though, on seeing Haytham return to full health in January 1758, Holden committed suicide on 28 January, as he was no longer able to cope with the injuries and emotional trauma inflicted upon him at Abou Gerbe.