The occasion for Shalmaneser's intervention in Babylonian affairs was furnished by internal dissension.[29] When Marduk-bêl-usâte, the brother of Marduk-zakir-shum, revolted, and divided the country into two armed camps, Shalmaneser readily responded to the latter's appeal for help, and marching southwards succeeded in defeating the rebels and in ravaging the districts under their control. On a second expedition in the following year he completed his work by slaying Marduk-bel-usâte in battle, and he was then acknowledged by Marduk-zakir-shum as his suzerain. In this capacity he toured through the principal cities of Akkad, offering sacrifices in the famous temples of Cuthah, Babylon, and Borsippa. He also led his army into Chaldea, and, after storming its frontier fortress of Bakâni, received the submission of its ruler, Adini, and heavy tribute from him and from Iakin, the Chaldean king of the Sea-Country further to the south. In his representation of the campaign Shalmaneser is portrayed marching through the country, and receiving tribute from the Chaldeans, which they carry from their cities and ferry across streams to deposit in the presence of the king and his officials. [Illustration FIGS. 62 AND 63. THE TRIBUTE OF THE CHALDEANS, In Fig. 62 Chaldeans are represented conveying tribute across a stream in boats; in Fig. 63 they deposit it at a bridge-head held by the Assyrians. (From the Gates of Shalmaneser.)] But Babylon did not long endure the position of a vassal state, and Shalmaneser's son and successor. Shamshi-Adad IV., attempted her reconquest, plundering many cities before he met with serious opposition. Marduk-balâtsu-ikbi, the Babylonian king, had meanwhile collected his forces, which included armed levies from Elam, Chaldea, and other districts. The two armies met near the city of Dûr-Papsukal, the Babylonians were totally defeated, and a rich booty fell to their conqueror. During a subsequent interregnum Erba-Marduk, the son of Marduk-shakin-shum, secured the throne, owing his election to his success in driving Aramean raiders from the cultivated fields of Babylon and Borsippa.[30] But he did not reign for long, and when Babylon continued to give trouble to Assyria, Adad-nirari IV., the successor of Shamshi-Adad, again subjugated a considerable portion of the country, carrying away Bau-akhi-iddina, the Babylonian king, as a captive to Assyria, together with the treasures of his palace.[31]