The Fox Cannon was a UNSC vehicle cut from Halo Wars. It was to be a self-propelled artillery vehicle, capable of firing five shells per minute, and with great accuracy due to satellite targeting over a distance greater than 50 kilometers. The Fox was equipped with a 175mm cannon that shot the M179 Projectile. Given its role, it was likely replaced by the Cobra.
Fox Cannon is part of the deleted material from the Halo games. During the development process, the developers are forced to remove some content from the final product. As such, many aspects of the games, such as vehicles, gameplay, and story elements, were not included in the finalized versions.