וַיְהִ֥י מִבְחַר־עֲמָקַ֖יִךְ מָ֣לְאוּ רָ֑כֶב וְהַפָּ֣רָשִׁ֔ים שֹׁ֖ת שָׁ֥תוּ הַשָּֽׁעְרָה׃
And it came to pass, when thy choicest valleys were full of chariots, And the horsemen set themselves in array at the gate,
Rashi on Isaiah
laid [siege] to the gate (Lit., laid to the gate.) They laid siege to the gates. There is a similar expression in Kings (II 20:12) in the war with Ben Hadad, “Lay on!” And they laid siege to the city.
Ibn Ezra on Isaiah
Thy valleys. The second person refers to Jerusalem. שת שתו.
Ibn Ezra on Isaiah
They prepare,9A. V., They set themselves in array. the forts, the trenches, and all the instruments of war.