What was the name of the first Assassin's Creed game released for the Nintendo DS?

The first Assassin's Creed game released for the Nintendo DS was Assassin's Creed: Altaïr's Chronicles.

Gameloft developed Altaïr's Chronicles as a prequel to the original Assassin's Creed. It was released in 2008 for Nintendo DS and follows Altaïr Ibn-La'Ahad before the events of the 2007 console game. Its story takes place during the Third Crusade and introduces a separate adventure involving the search for the Chalice.

The DS version uses side-scrolling action and platforming rather than reproducing the original game's large 3D cities. Its controls, structure, and presentation were adapted to the handheld system.

Assassin's Creed II: Discovery came later for Nintendo DS and iOS, while Bloodlines was developed for PlayStation Portable. Rebellion is a later mobile strategy game, so none of those titles was the first Nintendo DS release.