Which Assassin's Creed game first introduced dedicated naval combat as a major feature?

Assassin's Creed III first introduced dedicated naval combat as a major feature in the Assassin's Creed series.

The game includes naval missions in which the player commands the ship Aquila. These missions involve steering, firing broadside cannons, managing the ship's movement, and fighting enemy vessels in the Atlantic Ocean. Naval activities became one of the game's most distinctive additions.

Assassin's Creed III is set largely during the American Revolution and follows Connor, whose Mohawk name is Ratonhnhaké:ton. The naval sections connect his story to the North Atlantic frontier and provide a break from the game's land-based missions.

Earlier games included water travel and limited ship-related sequences, but they did not make structured naval combat a major recurring system. Assassin's Creed IV: Black Flag later expanded the idea dramatically, making ship exploration and combat central to its entire experience.