Which Assassin's Creed game is subtitled Black Flag?

Assassin's Creed IV is the game subtitled Black Flag.

Its full title is Assassin's Creed IV: Black Flag, and Ubisoft released it in 2013. The story follows Edward Kenway, a Welsh privateer and pirate who becomes involved in the Assassin-Templar conflict during the Golden Age of Piracy.

The game is set primarily in the Caribbean and features open-world sailing between islands and coastal settlements. Edward commands the ship Jackdaw, which can be upgraded with new weapons, stronger armor, and improved cargo capacity. Naval exploration and ship-to-ship combat are central parts of the experience.

Black Flag is sometimes confused with Assassin's Creed Rogue because both include pirate-era gameplay and naval combat. Rogue, however, follows Shay Cormac and was released in 2014. Black Flag's Roman numeral is IV because it is the fourth numbered main entry in the franchise.