In 539 BC Cyrus invaded Babylonia. A battle was fought at Opis in the month of June, where the Babylonians were defeated; and immediately afterwards Sippara surrendered to the invader. Two days after the capture of Sippara, "the soldiers of Cyrus entered Babylon without fighting". Cyrus did not arrive until the 3rd of "Marchesvan" (October), Gobryas having acted for him in his absence. Gobryas was now made governor of the province of Babylon.