Charles Ellicott Commentary Jeremiah 34:7

"when the king of Babylon`s army was fighting against Jerusalem, and against all the cities of Judah that were left, against Lachish and against Azekah; for these [alone] remained of the cities of Judah [as] fortified cities." — Jeremiah 34:7 (ASV)

Against Lachish, and against Azekah ... —The two cities are named in this book for the first time. Lachish was one of the strongest towns of the Amorites in the time of Joshua (Joshua 10:3; Joshua 10:5), and was situated in the Shephelah, or lowland district (Joshua 15:39). It was restored or fortified by Rehoboam, as a defence against the northern kingdom (2 Chronicles 11:9). Amaziah took refuge there on his flight from the conspiracy at Jerusalem (2 Chronicles 14:19; 2 Chronicles 25:27). It was taken by Sennacherib on his way from Assyria to Egypt, and made the monarch’s headquarters (2 Chronicles 32:9; 2 Kings 18:17). A slab at Kouyunjik (Layard’s Nineveh and Babylon, 149-152; Monuments of Nineveh, 2nd Series, Plates xxi, 24) represents the siege of Lakhisha by the armies of Sennacherib, and gives something like a ground-plan of the city.

Its site has not been identified with certainty, but ruins still known as Um-lakis are found between Gaza and Eleutheropolis. It is mentioned here as being, next to Jerusalem, one of the strongest fortresses of the kingdom of Judah, which thus far had resisted the attack of Nebuchadnezzar’s armies.

Azekah, less conspicuous in history, was also in the Shephelah region, and is named with other cities in Joshua 10:10-11; Joshua 15:35. The Philistines were encamped between it and Shochoh in the days of Saul (1 Samuel 17:1). It also was fortified by Rehoboam (2 Chronicles 11:9). Its site has not been ascertained, but Eusebius and Jerome speak of it as lying between Eleutheropolis and Jerusalem.