After the death of Colonel George Monro, the former Assassin Shay Cormac was formally inducted into the Colonial Rite of the Templar Order by its Grand Master, Haytham Kenway. After a few days, Cormac and Kenway met in New York, and after a brief discussion about First Civilization Temples, Haytham informed Shay about Assassin activity near the Fort of Louisbourg.
Shay was also informed about the Royal Navy officer and explorer, James Cook, and his usefulness to the Templars, despite the lack of knowledge of the Order's existence on the captain's part. Shay and his quartermaster, Christopher Gist, met with James Cook and Haytham aboard the former's Man O' War, HMS Pembroke. Cook informed the Templars that a Royal Navy fleet had already set sail for Louisbourg, but the he was worried about the French defenses. Grand Master Kenway insisted on attacking the fort, and eventually convinced Cook to participate. Cook in turn offered command of his ship to Shay, for the duration of the battle.
On the day of battle, HMS Pembroke was approaching Louisbourg, escorted by two frigates. As the ships neared the fort, mortars fired by the French Men O' War destroyed the escort ships. In response, Shay utilized the HMS Pembroke's own fire-power to sink the enemy ships.
After a successful retaliation, the ship of Assassin Adéwalé, the Experto Crede, led several fireships into the fray. Under the advice of Gist, Shay did not attack the Assassin's brig, focusing on the fireships instead. Eventually, the fireships were joined by French reinforcements, but were soon destroyed after British reinforcements arrived. This allowed to Royal Navy, which later arrived with an astonishing 40 Men O' War, to launch an offensive on the fort itself, and capture Louisbourg.
The Siege of Louisbourg proved to be the turning point of the Seven Years' War, weakening the French. Adéwalé's interference made him a target for the Templars, which was capitalized on by Shay and Haytham, who tracked down and eliminated him at Vieille Carrière.