Albert Barnes Commentary Jeremiah 33:4

"For thus saith Jehovah, the God of Israel, concerning the houses of this city, and concerning the houses of the kings of Judah, which are broken down [to make a defence] against the mounds and against the sword;" — Jeremiah 33:4 (ASV)

By ... by - Rather, against ... against. As the siege works of the enemy approached the walls, houses were pulled down to build inner fortifications. Swords are mentioned in Ezekiel 26:9 (translated as axes), as used for breaking down the towers in the walls. See Jeremiah 5:17, note.