1)
Here it says that that Retzin and Pekach ben Remalyahu struck Achaz and killed 120,000 from Yehudah in one day. Melachim II, 16:5 says that they could not fight [against Achaz]!
1.
Malbim (here and Melachim II, 16:5): From Yeshayah 7:1-6 it seems that when Retzin and Pekach ben Remalyahu each came by himself, he could not conquer Yerushalayim, but they ravaged other cities of Yehudah. When they joined together, they were unable [to depose Achaz and make Ben Tav'al king].
