'Fortified Cities' in the Bible

Declare in Judah and proclaim in Jerusalem, and say,“Blow the trumpet in the land;Cry aloud and say,‘Assemble yourselves, and let us goInto the fortified cities.’

“They will consume your harvest and [eat up] your bread;They will consume your sons and your daughters;They will consume your flocks and your herds;They will consume your vines and your fig trees.With the sword they will break down and demolish your fortified cities in which you trust.

Why are we sitting still [the people wonder]?Assemble yourselves, and let us enter the fortified citiesAnd let us die there,For the Lord our God has decreed our ruinAnd given us bitter and poisonous water to drink,Because we have sinned against the Lord.

when the army of the king of Babylon was fighting against Jerusalem and against all the remaining cities of Judah, against Lachish and Azekah, for these were the [only] fortified cities among the cities of Judah.