Bellona was the Roman goddess of war. She often fought alongside Mars, and different sources list Bellona as either his wife, his sister, or his daughter. She is often depicted wearing a war helmet and carrying a sword or a spear.
Latin lesson for the day: Bellona's name is derived from the Latin root bellum, which is also the root behind a number of English war-related words (antebellum, belligerent, bellicose)
E2 Dictionary of Classical Mythology