 Different accounts of Probus's death exist.According to Joannes Zonaras, the commander of the Praetorian Guard Marcus Aurelius Carus had been proclaimed, more or less unwillingly, emperor by his troops.Probus sent some troops against the new usurper, but when those troops changed sides and supported Carus, Probus' remaining soldiers assassinated him at Sirmium (September/October 282).