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

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

Released in 2012, Assassin's Creed III includes missions in which Connor Kenway commands a sailing ship and fights enemy vessels. These sequences take place in the Atlantic Ocean and combine wind direction, cannon fire, ship maneuvering, and boarding mechanics.

Naval gameplay became one of the most praised additions to Assassin's Creed III. Ubisoft later expanded the concept dramatically in Assassin's Creed IV: Black Flag, where sailing, ship upgrades, naval combat, and ocean exploration became central parts of the experience.

The distinction matters because Black Flag is often remembered as the series' defining naval game, but it did not introduce the feature. Assassin's Creed II and Brotherhood contain no comparable major naval-mission system. Assassin's Creed III's naval sections established the foundation for the later pirate-focused design.