2 Kings 16:5

came upto Jerusalem to war The plans which had been formed in the reign of Jotham (see 2 Kings 15:37) were now put into execution. And from Isaiah 7:2 we can see into what agitation the people of Judah were brought by the advance of the allied enemies. -It was told the house of David, saying, Syria is confederate with Ephraim (i.e. Israel). And his heart was moved and the heart of his people as the trees of the wood are moved with the wind".

they besieged Ahaz, but could not overcomehim] i.e. They never took Jerusalem (cf. Isaiah 7:1). This is the security which Isaiah was instructed to promise to Ahaz. But it is evident from the narrative of the Chronicler that much damage was done in the land by the invasion. He says (2 Chronicles 28:5) that Ahaz was delivered into the hand of the king of Syria, who smote him and carried away a great multitude of captives and brought them to Damascus, and he was also delivered into the hand of Pekah king of Israel, who slew in Judah a hundred and twenty thousand men in one day, and carried away captive two hundred thousand, women, sons and daughters, along with much spoil. We can understand the stir caused in Jerusalem by the approach of an army which had already inflicted such blows upon the land.