2 Kings 16:5

Then Rezin king of Syria ... to war. — This verse agrees almost word for word with Isaiah 7:1. The time is soon after the accession of Ahaz. “Jotham, the last of a series of strong and generally successful princes, had died at a critical moment, when Pekah and Rezin were maturing their plans against his kingdom. The opposing parties in northern Israel suspended their feuds to make common cause against Judah (Isaiah 9:21), and the proud inhabitants of Samaria hoped by this policy to more than restore the prestige forfeited in previous years of calamity (Isaiah 9:9). At the same time the Syrians began to operate in the eastern dependencies of Judah, their aim being to possess themselves of the harbour of Elath on the Red Sea, while the Philistines attacked the Judeans in the rear, and ravaged the fertile lowlands (Isaiah 9:12; 2 Kings 16:6). A heavy and sudden disaster had already fallen on the Judean arms, a defeat in which ‘head and tail, palm-branch and rush’ had been mown down in indiscriminate slaughter (Isaiah 9:14). Ahaz was no fit leader in so critical a time; his character was petulant and childish, his policy was dictated in the harem (Isaiah 3:12). Nor was the internal order of the state calculated to inspire confidence. Wealth, indeed, had greatly accumulated in the preceding time of prosperity, but its distribution had been such that it weakened rather than added strength to the nation. The rich nobles were steeped in sensual luxury, the court was full of gallantry, feminine extravagance and vanity gave the tone to aristocratic society (Isaiah 5:11; Isaiah 3:16; comp. Isaiah 3:12; Isaiah 4:4), which, like the noblesse of France on the eve of the Revolution, was absorbed in gaiety and pleasure, while the masses were ground down by oppression, and the cry of their distress filled the land (Isaiah 3:15; Isaiah 5:7).” — Prof. Robertson Smith.

They besieged Ahaz. — The allies wanted to compel Judah to join them in their attempt to throw off the burdensome yoke of Assyria, imposed in 738 B.C. (2 Kings 15:19); and thought the best way to secure this was to dethrone the dynasty of David, and set up a creature of their own — “the son of Tabeal” (Isaiah 7:6).

Could not overcome him. — Literally, they were not able to war, as in Isaiah 7:2. The allies could not storm the city, which had been strongly fortified by Uzziah and Jotham (2 Chronicles 26:9; 2 Chronicles 27:3).