Already, by early December, Persian outriders had reached the Median Wall. Next, turning its flank, Darius led his army over the Tigris, his soldiers clinging to horses, camels and inflated animal-skins. On 13 December 522 BC he met the army of Nebuchadnezzar III in battle, and routed it. Six days later, with a second victory, Darius completed his annihilation of the Babylonian forces.