Dan 11:6

11:6 the daughter of the king. Berenice, the daughter of Ptolemy II Philadelphus, 285–246 b.c.

to make an agreement. This is a marriage alliance (about 250 b.c.) between Antiochus II Theos (261–246 b.c.) of Syria and Ptolemy II of Egypt.

he and his arm shall not endure. Laodice, the former wife of Antiochus II, led a conspiracy that resulted in the death by poisoning of Berenice, Antiochus II, and their infant son.