In 1747, during the War of the Austrian Succession, Slater oversaw the hanging of the deserter Tom Smith and Haytham Kenway, who had been mistaken for Smith's accomplice. Haytham protested and demanded to see Braddock, but Slater ignored him, forcing Haytham to grab Slater's assistant with his legs and throw himself off. The platform collapsed and the assistant died, but Smith had already been executed.
During the army's retreat following the French victory at the siege of Bergen op Zoom, a young man insulted Braddock after refusing to let his family come on board a boat. Angered, Braddock ordered Slater and his new assistant to kill the whole family.
Disgusted by the vicious display he witnessed, Haytham later avenged the family in 1754, after encountering Slater in Boston.
- In the novel Assassin's Creed: Forsaken, Haytham killed Slater while Braddock's regiment marched through Boston to enlist new recruits. When Slater broke off from the rest of the soldiers to relieve himself, Haytham crept up behind him and killed him, then used his uniform to blend with the other soldiers so that he could speak to John Pitcairn.