But Assyria was long in recovering from the effects of the revolt, which had shaken her to the foundations. The dynasty itself never recovered. Samas-Rimmon, indeed, at the head of the army which had overcome his brother, continued the military policy of his predecessors; the tribes of Media and southern Armenia were defeated, and campaigns were carried on against Babylonia, the strength of which was now completely broken. In B.C. 812 Babylon was taken, but two years later Samas-Rimmon himself died, and was succeeded by his son Rimmon-nirari III. His reign was passed in constant warfare on the frontiers of the empire, and in B.C. 804 Damascus was surrendered to him by its king Mariha, who became an Assyrian tributary. In the following year a pestilence broke out, and when his successor, Shalmaneser III., mounted the throne in B.C. 781, he found himself confronted by a new and formidable power, that of Ararat or Van. The eastern and northern possessions of Assyria were taken from her, and the monarchy fell rapidly into decay. In B.C. 763 an eclipse of the sun took place on the 15th of June, and was the signal for the outbreak of a revolt in Assur, the ancient capital of the kingdom. It spread rapidly to other parts of the empire, and though for a time the government held its own against the rebels, the end came in B.C. 745. Assur-nirari, the last of the old dynasty, died or was put to death, and Pulu or Pul, one of his generals, was proclaimed king on the 13th of Iyyar or April under the name of Tiglath-pileser III.

Tiglath-pileser III. was the founder of the Second Assyrian empire, which was based on a wholly different principle from that of the first. Occupation and not plunder was the object of its wars. The ancient empire of Babylonia in western Asia was to be restored, and the commerce of the Mediterranean to be diverted into Assyrian hands. The campaigns of Tiglath-pileser and his successors were thus carried on in accordance with a deliberate line of policy. They aimed at the conquest of the whole civilised world, and the building up of a great organisation of which Nineveh and its ruler were the head. It was a new principle and a new idea. And measures were at once adopted to realise it.

The army was made an irresistible engine of attack. Its training, discipline, and arms were such as the world had never seen before. And the army was followed by a body of administrators. The conquered population was transported elsewhere or else deprived of its leaders, and Assyrian colonies and garrisons were planted in its place. The administration was intrusted to a vast bureaucracy, at the head of which stood the king. He appointed the satraps who governed the provinces, and were responsible for the taxes and tribute, as well as for the maintenance of order. The bureaucracy was partly military, partly civil, the two elements acting as a check one upon the other.

But it was necessary that Ararat should be crushed before the plans of the new monarch could be carried out. The strength of the army was first tested in campaigns against Babylonia and the Medes, and then Tiglath-pileser marched against the confederated forces of the Armenian king. A league had been formed among the princes of northern Syria in connection with that of the Armenians, but the Assyrian king annihilated the army of Ararat in Comagênê, and then proceeded to besiege Arpad. Arpad surrendered after a blockade of three years; Hamath, which had been assisted by Azariah of Judah, was reduced into an Assyrian province; and a court was held, at which the sovereigns of the west paid homage and tribute to the conqueror (B.C. 738). Among these were Rezon of Damascus and Menahem of Samaria. Tiglath-pileser was still known in Palestine under his original name of Pul, and the tribute of Menahem is accordingly described by the Israelitish chronicler as having been given to Pul.

The Assyrian king was now free to turn the full strength of his forces against Ararat. The country was ravaged up to the very gates of its capital, the modern Van, and only the strong walls of the city kept the invader out of it. The Assyrian army next moved eastward to the southern shores of the Caspian, striking terror into the Kurdish and Median tribes, and so securing the lowlands of Assyria from their raids. The affairs of Syria next claimed the attention of the conqueror. Rezon and Pekah, the new king of Samaria, had attempted to form a league against Assyria; and, with this end in view, determined to replace Ahaz, the youthful king of Judah, by a creature of their own. Ahaz turned in his extremity to Assyrian help, and Tiglath-pileser seized the opportunity of accepting the vassalage of Judah, with its strong fortress of Jerusalem, and at the same time of overthrowing both Damascus and Samaria. Rezon was closely besieged in his capital, while the rest of the Assyrian army was employed in overrunning Samaria, Ammon, Moab, and the Philistines (B.C. 734). Pekah was put to death, and Hosea appointed by the Assyrians in his place. After a siege of two years, Damascus fell in B.C. 732, Rezon was slain, and his kingdom placed under an Assyrian satrap. Meanwhile Tyre was compelled to purchase peace by an indemnity of 150 talents.

Syria was now at the feet of Nineveh. A great gathering of the western kings took place at Damascus, where Tiglath-pileser held his court after the capture of the city, and the list of those who came to do homage to him includes Jehoahaz or Ahaz of Judah, and the kings of Ammon, Moab, Edom, and Hamath. Hosea, it would seem, was not yet on the Israelitish throne.

The old empire of Babylonia was thus restored as far as the Mediterranean. All that remained was for the Assyrian usurper to legitimise his title by occupying Babylon itself, and there receiving the crown of Asia. In B.C. 731, accordingly, he found a pretext for invading Babylonia and seizing the holy city of western Asia. Two years later he "took the hands" of Bel-Merodach, and was thereby adopted by the god as his own son. But he did not live long to enjoy the fruits of his victories. He died December B.C. 727, and another usurper, Ululâ, possessed himself of the throne, and assumed the name of Shalmaneser IV. His reign, however, was short. He died while besieging Samaria, which had revolted after the death of its conqueror, and in December B.C. 722, a third general seized the vacant crown. He took the name of the old Babylonian monarch, Sargon, and the court chroniclers of after-days discovered that he was a descendant of the legendary kings of Assyria. His first achievement was the capture of Samaria. Little spoil, however, was found in the half-ruined city; and the upper classes, who were responsible for the rebellion, were carried into captivity to the number of 27,280 persons. The city itself was placed under an Assyrian governor.

Sargon found that the empire of Tiglath-pileser had in great measure to be re-conquered. Neither Tiglath-pileser nor his successor had been able to leave the throne to their children, and the conquered provinces had taken advantage of the troubles consequent on their deaths to revolt. Babylonia had been lost. Merodach-baladan, the Chaldæan prince, had emerged from the marshes of the south and occupied Babylon, where he was proclaimed king immediately after Shalmaneser's death. For twelve years he reigned there, with the help of the Elamites, and one of the first tasks of Sargon was to drive the latter from the Assyrian borders. Sargon had next to suppress a revolt in Hamath, as well as an invasion of Palestine by the Egyptians. The Egyptian army, however, was defeated at Raphia, and the Philistines with whom it was in alliance returned to their allegiance to the Assyrian king.