ירמיהו, פרק נ״ב, פסוק ד׳

The Babylonian campaign to conquer Jerusalem begins against a backdrop of weak local leadership. The invasion is launched during the tenth month, which is the month of Tevet [ביאור שטיינזלץ], during the ninth year of King Zedekiah's rule [מצודת דוד].

The war brought upon the city was overwhelming. Zedekiah found himself in a desperate position, lacking any significant military force to fight back against Nebuchadnezzar and the Babylonian army [ביאור שטיינזלץ].

To secure a decisive victory, the Babylonians constructed a military siege system around Jerusalem [רש״י]. There are different understandings of how this fortification was actually built. One approach describes it as a dedicated attack tower erected right in front of the city to help capture it [מצודת דוד ומצודת ציון]. Another perspective views it as a continuous perimeter structure, such as a low wall or a raised rampart, that completely surrounded the city walls and sealed Jerusalem off from all sides [ביאור שטיינזלץ].