The Battle of the Margus was fought in July 285 between the armies of Roman Emperors Diocletian and Carinus in the valley of the Margus River (today Great Morava) in Moesia (present day Serbia). Carinus led the larger force, but the loyalty of this army was definitely questionable. Carinus had allegedly alienated men whose support his success depended upon, including mistreating the Senate and its womenfolk and seducing the wives of his officers. The exact circumstances of the battle are in doubt, but it is known for certain that Carinus was killed in the course of the battle, most probably by one of his own officers.