From The Art and Popular Culture Encyclopedia
Mars was the Roman god of war, the son of Juno and Jupiter, husband of Bellona, and the lover of Venus. He was the most prominent of the military gods that were worshipped by the Roman legions. The martial Romans considered him second in importance only to Jupiter (their main god). His festivals were held in March (named for him) and October. As the word Mars has no Indo-European derivation, it is most likely the Latinised form of the agricultural Etruscan god Maris. Initially Mars was a Roman god of fertility and vegetation and a protector of cattle, fields and boundaries and farmers. In the second century BC, the conservative Cato the Elder advised "For your cattle, for them to be healthy, make this sacrifice to Mars Silvanus you must make this sacrifice each year". (Cato, De Agri Cultura) Mars later became associated with battle as the growing Roman Empire began to expand, and he came to be identified with the Greek god Ares. Unlike his Greek counterpart, Mars was generally revered and rivaled Jupiter as the most honoured god. He was also the tutelary god of the city of Rome. As he was regarded as the legendary father of Rome's founder, Romulus, it was believed that all Romans were descendants of Mars.