Which Assassin's Creed game was the first in the series to feature naval combat as a major gameplay system?

Assassin's Creed III was the first Assassin's Creed game to feature naval combat as a major gameplay system.

The game introduces Captain Edward Kenway's naval missions through the story of Connor, also known as Ratonhnhaké:ton. Players command a ship, maneuver under sail, fire cannons, and engage enemy vessels in battles set along the Atlantic coast and other waters.

Earlier entries included limited water travel or swimming, but they did not make ship-to-ship combat a substantial, repeatable system. Assassin's Creed III therefore laid the mechanical foundation for Assassin's Creed IV: Black Flag, which made sailing and naval warfare central to its entire design.

The distinction matters because Black Flag is more famous for naval combat, but it was not the first series entry to introduce the feature. Assassin's Creed III was released in 2012 and is set during the American Revolution. Its naval missions helped demonstrate that the series could expand beyond city rooftops and land-based assassination contracts.