In the days of Ahaz - Ahaz began to reign about 738 years before Christ. By a comparison of 2 Kings 16:5, , with 2 Chronicles 28:5, etc., it will be seen that Judea was twice invaded by Rezin and Pekah in the reign of Ahaz; see the Analysis of the chapter.
That Rezin - This confederacy was formed in the time of Jotham; 2 Kings 15:37. But it was not carried into execution during his reign. It is evident from this place, that it was executed in the early part of the reign of Ahaz; probably in the first or second year of his reign.
Syria - - ארם 'ărâm so called from Aram Genesis 10:22-23, a son of Shem, and who populated its chief provinces. It comprehended the country lying between the Euphrates east, the Mediterranean west, Cilicia north, and Phenicia, Judea, and Arabia south; see the notes at Isaiah 17:1-14. Syria of the two rivers is Mesopotamia. Syria of Damascus, so called because Damascus was its capital, extended eastward along Mount Libanus, but its limits varied according to the power of the princes of Damascus. After the reign of the Seleucidae, Syria came to denote the kingdom or region of which Antioch was the capital. Here it denotes the Syria lying around Damascus, and of which Damascus was the capital. - “Calmet.”
King of Israel - Of the ten tribes, called the kingdom of Israel, or Samaria; Note, Isaiah 1:1.
Went up - Jerusalem was situated on hills, and on the highest part of the land. But it is possible that this language is derived from the fact that it was the capital. The language is used even when the region from which the traveler comes does not lie lower than the city. Thus it is not uncommon to speak of “going up” to London, Paris, etc.
Could not prevail - Hebrew, ‹Could not fight against it,‘ that is, with happy result, or with success. He was not able to take it. That the allied kings really besieged Ahaz, is evident from 2 Kings 16:5: They ‹came up to Jerusalem to war, and they besieged Ahaz, but they could not overcome him.‘ The reason why they could not take Jerusalem was, probably, not only because it was a strong place and well defended, but because there was intelligence that their own dominions were threatened with an invasion by the Assyrians, and they could not protract their siege of Jerusalem long enough to take it.