Why did King Ahaz make an alliance with the Assyrians

Assyria was clearly intent on a policy of imperial expansion and by 734 BCE the Assyrian king Tiglath-pileser was drawn to campaign against a coalition of rebellious vassals that included Tyre, Aram (Damascus) and Israel.

Ahaz came under pressure from the rebel states to join their cause, and when he sought to remain neutral, the rebels laid siege to Jerusalem with the intention of replacing him with a more compliant ruler (2 Kings 16:5,7-9; lsaiah 7:1-6).

In the end, Ahaz only had the choice of which side he would take, in a war that he had wanted to avoid. History shows that if he joined the coalition of Tyre, Aram and Israel, then Assyria would have defeated him anyway. To avoid defeat by the rebels, he sent a message to Tiglath-pileser: “I am your servant and your son. Come up, and rescue me from the hand of the king of Aram and from the hand of the king of Israel, who are attacking me” (2 Kings 16:7).