Ahaz in Fausset's Bible Dictionary

Ahaz ("possessor".) Son of Jotham; ascended the throne of Judah in his 20th year (2 Kings 16:2), a transcriber's error for 25th year; as read in the Septuagint, Syriac, and Arabic (2 Chronicles 28:1); for otherwise Hezekiah his son would be born when Ahaz was 11 years old. Rezin, king of Damascus, and Pekah of Israel leagued against Judah, to put on the throne the son of Tabeal, probably a Syrian (Isaiah 7:6). Isaiah and Shear-jashub his son (whose name means "the remnant shall return" was a pledge that, notwithstanding; heavy calamity, the whole nation should not perish), together met Ahaz by Jehovah's direction at the end of the conduit of the upper pool, and assured him that Rezin's and Pekah's evil counsel should not come to pass; nay, that within 65 years Ephraim (Israel) should cease to be a people. It is an undesigned propriety in Isaiah 7, and therefore a mark of truth, that the place of meeting was the pool; for there it was we know, from the independent history in Chronicles, that Hezekiah his son, subsequently in Sennacherib's invasion, with much people stopped the waters without the city to cut off the enemy's supply (2 Chronicles 32:3-5). The place was appropriate to Isaiah's message from God that their labors were unnecessary, for God would save the city; it was also suitable for addressing the king and the multitude gathered for the stopping of the waters there. Isaiah told Ahaz to "ask a sign," i.e. a miraculous token from God that He would keep His promise of saving Jerusalem. ..

Link: https://bible-history.com/faussets/A/Ahaz/