A 1st-century Mars Ultor, found in the Forum of Nerva (Capitoline Museums, Rome). In ancient Roman religion and myth, Mars (Latin: Mrs, [mars) was the god of war and also an agricultural guardian, a combination characteristic of early Rome. Augustus created the cult of 'Mars the Avenger' to mark two occasions: his defeat of the assassins of Caesar at Philippi in 42 BC, and the negotiated return of the Roman battle standards that had been lost to the Parthians at the Battle of Carrhae in 53 BC.