Silas Thatcher was born in London to an affluent merchant, who purchased a commission for him in the British army in 1737, and he became a cruel officer whom nobody wished to serve under. He was posted at the Boston Neck, at the Southgate Fortress, where he ran slave trade operations with the Iroquois population, and he demanded protection money from several merchants, one of the people including Benjamin Church. When Church refused, he beat him and left him to be shot by his guards, but the guards were all killed by an assassin known as Haytham Kenway.
Soon, a group of mutinous redcoats attacked the fort, freeing the slaves in the wagon train heading to the fort's gates, and the redcoats fought with the loyal soldiers in the fort, and Thatcher said that anyone who would go near the exit was to be shot dead. Thatcher was shot in the head by one of them, who was rumored to have been Benjamin Church.