Church was born in Newport in Great Britain's Province of Rhode Island. He became a merchant in Boston, and in 1754, he was beaten by General Silas Thatcher, commander of the Southgate Fortress, because he refused to pay him protection money, and soon after, joined the Templar Order when Haytham Kenway rescued him from Thatcher's thugs. When Kenway attacked the fortress, with his allies dressed as redcoats in order to kill Silas Thatcher and thus free some Mohawk slaves there, he requested that he be the one to kill Thatcher. He shot the hapless Thatcher as he was held by Haytham, and Haytham, Church, and other members of the secret society headed to the Mohawk Great Temple, where the Templar "New World" was supposed to be centered.
In 1770, Church recruited Midshipman Nicholas Biddle into the Templar Order at Martha's Vineyard and, in 1775, joined the Continental Army during the American Revolutionary War. He was made Surgeon-General, but he was imprisoned for sending letters to Tories about US troop strengths. In late 1777, at Valley Forge, General George Washington suspected him of stealing supplies for the British, leading to a court martial. Around this time, he abandoned the Templar secret society and began to look for ways to survive on his own.
When Haytham Kenway encountered his son Ratonhnhake:ton at a church, they formed a temporary alliance against Church, with Connor looking for clues as to where he had gone. He followed a convoy of mercenaries to Church's camp, where he eavesdropped on their conversations, and heard that he was in New York, trying to keep a low profile.
DeathAfter interrogating an imposter of Church in New York, Haytham Kenway and Ratonhnhake:ton found out that he was on a ship bound for French Martinique, the Welcome, a trading sloop that carried the stolen supplies. Five British schooners ambushed their ship HMS Aquila, and Church attempted to use the ambush as cover, but the British ships were destroyed and chain shot blew up the sails of Welcome. Haytham and Connor boarded the sloop and slew three officers while the crews fought on the deck, and they searched for Church.
Haytham and Connor entered the captain's cabin and found Church there, and Haytham repeatedly punched Church in the face, savaging him. Connor then stabbed him in the chest with a hidden dagger, and Church's final words were that "the patriots fight with muskets of British steel, wrap their faces with British bands...we (the British) do the work, they reap the rewards...do you think the Crown has no cause?...you should know better than that...think of that the next time when you think that your work alone benefits the greater good...", and he died, suffocating on his blood.