His second campaign was also directed towards the Mitanni district, which had been invaded during his absence by a force of Hittites, about 4000 strong. The invaders submitted to him as soon as he drew near, and he added them to his standing army. Subsequent operations towards the north restored the pre-eminence of Assyria in the Nairi country, on the shores of Lake Van, in Armenia, where Tiglath-pileser captured no fewer than twenty-three petty kings. These he liberated after they had taken the oath of allegiance and consented to pay annual tribute. In his fourth year the conqueror learned that the Aramaeans were crossing the Euphrates and possessing themselves of Mitanni, which he had cleared of the Hittites. By a series of forced marches he caught them unawares, scattered them in confusion, and entered Carchemish, which he pillaged. Thereafter his army crossed the Euphrates in boats of skin, and plundered and destroyed six cities round the base of the mountain of Bishru. While operating in this district, Tiglath-pileser engaged in big-game hunting. He recorded: "Ten powerful bull elephants in the land of Haran and on the banks of the Khabour I killed; four elephants alive I took. Their skins, their teeth, with the living elephants, I brought to my city of Asshur."[419] He also claimed to have slain 920 lions, as well as a number of wild oxen, apparently including in his record the "bags" of his officers and men. A later king credited him with having penetrated to the Phoenician coast, where he put to sea and slew a sea monster called the "nakhiru". While at Arvad, the narrative continues, the King of Egypt, who is not named, sent him a hippopotamus (pagutu). This story, however, is of doubtful authenticity. About this time the prestige of Egypt was at so low an ebb that its messengers were subjected to indignities by the Phoenician kings. The conquests of Tiglath-pileser once more raised the Mesopotamian question in Babylonia, whose sphere of influence in that region had been invaded. Marduk-nadin-akhe, the grandson of Nebuchadrezzar I, "arrayed his chariots" against Tiglath-pileser, and in the first conflict achieved some success, but subsequently he was defeated in the land of Akkad. The Assyrian army afterwards captured several cities, including Babylon and Sippar.