Later, Herodotus (I, 188) refers to Cyrus the Persian as fighting against the son of Labynetus and Nitocris.

In a book of the Yale Oriental Series entitled Nabonidus and Belshazzar, Professor R. P. Dougherty advances the supposition that Nitocris was the daughter of Nebuchadnezzar and that therefore Nabonidus (Labynetus) was Nebuchadnezzar’s son-in-law. (1929, p. 63; see also pp. 17, 30.) In turn, the “son” of Nitocris and Nabonidus (Labynetus), mentioned by Herodotus, is thought to be Belshazzar, against whom Cyrus did indeed fight. Although based on much deductive and inductive reasoning, this argument might explain the reason for Nabonidus’ ascension to the Babylonian throne. It would also harmonize with the Biblical fact that Nebuchadnezzar is referred to as the “father” of Nabonidus’ son Belshazzar (Da 5:11, 18, 22), the term “father” at times having the meaning of grandfather or ancestor. This view would make Belshazzar a grandson of Nebuchadnezzar.​—See, however, BELSHAZZAR.

In a number of prisms Nabonidus associates his firstborn son, Belshazzar, with himself in his prayers to the moon-god. (Documents From Old Testament Times, edited by D. W. Thomas, 1962, p. 73) An inscription shows that in his third year, prior to going out on a campaign that resulted in the conquest of Tema in Arabia, Nabonidus appointed Belshazzar to kingship in Babylon.

Regarding Cyrus’ advance, the Chronicle states that, following a victory at Opis, he captured Sippar (c. 60 km [37 mi] N of Babylon) and “Nabonidus fled.” Then follows the account of the Medo-Persian conquest of Babylon, and it is stated that upon Nabonidus’ return there he was taken prisoner. (Ancient Near Eastern Texts, p. 306) The writings of Berossus, Babylonian priest of the third century B.C.E., relate that Nabonidus had gone out to engage Cyrus’ forces in battle but was defeated. They further tell that Nabonidus took refuge in Borsippa (SSW of Babylon) and that, after Babylon fell, Nabonidus surrendered to Cyrus and was thereafter deported to Carmania (in southern Persia). This account would coincide with the Biblical record at Daniel chapter 5, which shows that Belshazzar was the acting king in Babylon at the time of its overthrow.

As to the absence of any direct mention of Nabonidus in chapter 5 of Daniel, it may be noted that Daniel’s description deals with only a very few events prior to the fall of Babylon, and the actual collapse of the empire is set forth in but a few words. However, his rulership is apparently indicated at Daniel 5:7, 16, 29, where Belshazzar offers to make Daniel the third ruler in the kingdom, implying that Nabonidus was the first and Belshazzar the second. Thus, Professor Dougherty comments: “The fifth chapter of Daniel may be regarded as comporting with fact in not giving any place to Nabonidus in the narrative, for he seems to have had no share in the events which transpired when Gobryas [at the head of Cyrus’ army] entered the city.”​—Nabonidus and Belshazzar, pp. 195, 196; see also pp. 73, 170, 181; see Da 5:1, ftn.

Also of interest are the evident references to Belshazzar in the Chronicle. Although Belshazzar is not specifically named, in the light of later portions of the Chronicle (col. II, lines 5, 10, 19, 23), column 1, line 8, is construed by Sidney Smith, in his Babylonian Historical Texts: Relating to the Capture and Downfall of Babylon (London, 1924, p. 100), as showing that Nabonidus entrusted kingship to Belshazzar, making him coregent. Repeatedly the Chronicle states that the ‘crown prince was in Akkad [Babylonia]’ while Nabonidus himself was at Tema (in Arabia). However, the fact that Belshazzar is not mentioned by name nor is his death referred to in the Nabonidus Chronicle in no way brings into question the accuracy of the inspired book of Daniel, where the name Belshazzar appears eight times and his death concludes the graphic account of Babylon’s overthrow narrated in chapter 5. Quite to the contrary, cuneiform experts admit that the Nabonidus Chronicle is extremely brief, and in addition, as shown above, they are of the opinion that it was written to defame Nabonidus, not to give a detailed history. Indeed, as R. P. Dougherty says in his work Nabonidus and Belshazzar (p. 200): “The Scriptural account may be interpreted as excelling because it employs the name Belshazzar.”​—Italics ours.