The video confirms a new Assassin who lives in colonial America during 1777 and fights several soldiers before looking out upon a soldier-filled battlefield.
It will feature a new lead named Connor, the offspring of an English father and Native American mother.
New abilities are expected to feature in the game, such as climbing trees and hunting wildlife, while recent screenshots showing various seasons suggest a story that takes place over several years.
"Assassin's Creed III features the franchise's most expansive setting so far, along withan exciting new hero and exponentially more gameplay," said Ubisoft chief executive officer Yves Guillemot.
"Whether you're a longtime fan of Assassin's Creed or if you're new to the franchise, you're going to be blown away by the scale and marvel of Assassin's Creed III."
Ubisoft president Yves Guillemot previously said that this latest Assassin's Creed title will be the "biggest to date".
An unofficial Assassin's Creed film recently appeared in India.
Assassin's Creed 3 will be released for Xbox 360, PC, PlayStation 3 and Wii U on October 31 worldwide.
View screenshots of Assassin's Creed 3 below: