About 147 BC he returned to Syria with a force of Cretan mercenaries led by a man called Lasthenes, while Alexander Balas was occupied with a revolt in Cilicia.

By late 145, Demetrius II had expelled all Ptolemaic troops from Syria and reasserted Seleucid control by leading his own forces all the way down to the Egyptian border.

One of these officials, the general Diodotus, fled into Arabia, where he secured the infant son of Alexander Balas and proclaimed him king as Antiochus VI Dionysus.

By means of adroit diplomacy and grants of extensive freedoms, Demetrios II was able to secure Jonathan's brother Simon Thassi as a close ally.

[21][22] Mithridates I, king of Parthia had taken advantage of the conflict between Demetrius and Tryphon to seize control of Susa and Elymais in 144 and of Mesopotamia in mid-141 BC.

As late as 140 vassal rulers of Persis, Elam, and even Bactria sent auxiliary troops (mostly persians and babylonians) to support Demetrius II in his war against the Parthians.

However, Demetrius was restless and twice tried to escape from his exile in Hyrcania on the shores of the Caspian Sea, once with the help of his friend Kallimander, who had gone to great lengths to rescue the king: he had travelled incognito through Babylonia and Parthia.

Now Phraates II made what he thought was a powerful move: he released Demetrius, hoping that the two brothers would start a civil war.

Phraates II sent people to pursue Demetrius, but he managed to safely return home to Syria and regained his throne and his queen as well.

He was apparently unpopular, perhaps from memories of his humiliating defeat and general discontent with the decline of the Empire, and perhaps from resentment that he had lived while so many Seleucid soldiers and family members sent to Parthia had died.

[27] At the time in Ptolemaic Egypt, a power struggle developed between Queen Cleopatra II and her brother king Ptolemy VIII.

A modern historian, John Grainger, defends it as a reasonable gamble: small forces had set off waves of defections before in recent history, so if Ptolemy VIII was truly as unpopular as reported, it might work.

More generally, the geopolitical situation for both the Seleucids and Ptolemys was desperate enough that uniting the remaining great Greek states might be the only way for them to maintain their relevance, given that Antigonid Macedonia had been crushed by Rome in the preceding decades.

Demetrius II camped outside the fortress of Pelusium, the gateway to Egypt, but Ptolemy VIII's troops remained loyal; there was no mass defection.

King Ptolemy VIII reacted by finding another potential Seleucid royal claimant to undermine the obviously hostile Demetrius II.

He was succeeded by the victorious usurper, Alexander II, while his queen, Cleopatra Thea, ruled in Ptolemais Akko in co-regency with two of their sons, Seleucus V Philometor and Antiochus VIII Grypus.