During his youth and like his father before him, Cudgel Cormac was trained by his grandfather, Shay Cormac, learning to master Freerunning and Eagle Vision. Later, he also inherited the air rifle of the Cormacs, which Shay had stolen from the Master Templar Lawrence Washington when he was still an Assassin more than a century ago.
By 1863, Cormac was the feared barman of one of New York City's pubs, where he was acting as the Templar contact with the gangs, being a trusted agent of Grand Master William M. Tweed. As such, he was tasked to convince the other gangs to participate in the riots organized by the Templars to turn the tide of the American Civil War in their favor. The night before the riots were scheduled to start, a letter of Tweed was delivered to Cormac, instructing him to stop an Assassin from stealing a Piece of Eden rumored to be hidden in the Aztec Club and to bring the artifact to his house.
Later, the Templar ambushed the Assassin Varius as he was leaving the Aztec Club with a Dagger of Eden, seizing the artifact from his paralyzed foe but sparing his life. He then left as the riots were starting in the city to watch the chaos from afar on a church's bell tower, prudently staying out of trouble and determined to bring the artifact to his master after sunset. While he agreed that the black citizens of New York were a necessary, yet sad, casualty of the Templar agenda, Cormac nevertheless decided to save the children of a black orphanage after it was set ablaze by rioters.
Eventually, as he reached Tweed's estate, the Templar discovered that having been guided by one of Tweed's servant, Eliza, Varius was also in the house, and the two resumed their fight. They freeran on the roofs of the city while brawling until Cormac inadvertently used the power of the artifact on Varius while ranting about his Templar ideals, throwing a knife at the confused Assassin, which hit him in the stomach.
However, as Cormac was about to finish the critically injured Assassin, Eliza, who followed them, used the rifle that Cormac lost during the fight to shoot a paralyzing dart at the Templar. Enraged by the death of her father who was beaten to death during the riots, Eliza threatened the powerless Templar with the Dagger to his throat, knowing he was responsible. She nevertheless spared him, promising to return for him and Tweed later, before vowing to join the Assassins and accomplish the mission of Varius delivering the Dagger to General Ulysses S. Grant.