When Sauron returned after escaping Númenor's destruction, he attacked the Exiles of Numenor, and his forces took Minas Ithil by storm. But the Last Alliance of Elves and Men defeated Sauron, and Minas Ithil was restored. As a part of the kingdom of Gondor, Minas Ithil stood as a watchtower on the borders of Mordor for nearly two thousand years.
But in the year 1980 of the Third Age, the Nazgûl returned to Mordor (after the defeat of the Witch-king in the north of Middle-earth). The Ringwraiths laid siege to Minas Ithil shortly after their return, and they took the city for their master, Sauron (who was still hidden at the time). Minas Ithil was occupied by fell creatures, and it changed into a foul, evil place. The city was renamed Minas Morgul which translates as "Tower of Dark Sorcery".
After the events of The Return of the King Minas Morgul was destroyed as it had become too foul for human habitation.