It came [to Jeremiah] also in the days of Jehoiakim the son of Josiah, king of Judah, [continuing] until the end of the eleventh year of Zedekiah the son of Josiah, king of Judah, [and continuing] until the exile of [the people of] Jerusalem in the fifth month (July-August, 586 b.c.).

and in the eleventh year of Zedekiah, in the fourth month, on the ninth day of the month, they breached the wall and broke into the city.

So the city was besieged until the eleventh year of King Zedekiah.