Adam Clarke on Daniel 11:22

And with the arms of a flood - The arms which were overflown before him were his competitors for the crown. They were vanquished by the forces of Eumenes and Attalus; and were dissipated by the arrival of Antiochus from Athens, whose presence disconcerted all their measures.

The prince of the covenant - This was Onias, the high priest, whom he removed, and put Jason in his place, who had given him a great sum of money; and then put wicked Menelaus in his room, who had offered him a larger sum. Thus he acted deceitfully in the league made with Jason.