Jeremiah 39:2

39:2 It lasted until the ninth day of the fourth month of Zedekiah’s eleventh year. ¹  On that day they broke through the city walls.

Jeremiah 52:5

52:5 The city remained under siege until Zedekiah’s eleventh year.

[39:2]  ¹ sn According to modern reckoning that would have been July 18, 586 b.c. The siege thus lasted almost a full eighteen months.