Which Call of Duty game was the first to feature a cooperative campaign for four players?

Which Call of Duty game was the first to feature a cooperative campaign for four players? The correct answer is Call of Duty: World at War.

Released in 2008, World at War was the first Call of Duty game to include a cooperative mode supporting up to four players online. Players could work through campaign missions together rather than playing only as a solo soldier.

On consoles, the game supported up to two players through split-screen, while online play allowed four players. This cooperative campaign was a major addition to the franchise and expanded the traditional single-player experience.

Black Ops III later became known for a campaign designed around four-player cooperative gameplay, with larger and more open levels. However, it was not the first Call of Duty title to offer four-player campaign cooperation. That feature debuted in World at War.