Silas Thatcher

Silas was a high ranking officer within the British Army, who was also a member of the Templar Order.

According to information that was gathered by a presumed ally of the Assassin Connor Kenway, Silas intended to lead a small party of soldiers to ambush a Continental outpost. Following this, Connor infiltrated the fort that Silas was stationed within and assassinated him with the bayonet of a musket.

Source

 * Assassin's Creed III - E3 Frontier Gameplay Demo