We read here as well as in the next verses how Antiochus’s self-confidence will grow. He will stage an attack outside of his kingdom, namely against Egypt. He will gather a large army and march against the king of the south, the king of Egypt.
At that time, Egypt is ruled by a son of Cleopatra I. Cleopatra is a sister of Antiochus. So this is also a family battle. A great battle takes place in which Antiochus is victorious.
25 And he shall stir up his power and his heart against the king of the south with a great army. And the king of the south shall wage war with an exceedingly great and mighty army, but he shall not stand, for plots shall be devised against him.