Tower of Heaven Slave Revolt is an event which took place in the year X776 in the Tower of Heaven in which the slaves of the tower rebelled against their oppressors.
In the year X776, a group of children are caught trying to escape the Tower of Heaven. One of the children, Erza Scarlet, is wrongly accused of leading the escape and is separated from the group and tortured. One of her friends, Jellal Fernandes, manage to get his hands on some weapons and went to save Erza. He successfully defeated multiple guards and found her alone in a cell, with wounds all over her body and her right eye missing. Jellal tries to encourage Erza to fight with him. However, one of the guards arrives and captures Jellal, wanting to punish him for killing three guards. With Jellal captured, the guard decides to return Erza to her friends. Remembering Jellal's words and seeing her friends suffering, Erza decides to fight.
Erza grabs the one of the guards' weapon and begins to attack them, telling the other prisoners that in order to get freedom, they need to fight. Her actions and words inspire the others and the prisoners decide to fight for their freedom. The prisoners manage to get a hold of some weapons and begin to fight the guards. During the fight, Mages join in as reinforcements for the guards, easily gaining the advantage against the slaves. While the other slaves retreat, Erza tries to rally them together, unaware that she is being targeted by one of the Mages. However, Rob, Erza's close friend and mentor, saves Erza by covering her with his body. The power of the spell kills Rob, triggering the birth of Erza's Magic. With her new found power, Erza manages to defeat the enemies, and rally the slaves back together.
With her Magic, Erza easily defeats the remaining enemies and arrives at Jellal's cell. Erza then unties Jellal and tells him that they are leaving the island with everybody, completely unaware that Jellal is being possessed by the Dark Mage Zeref. Jellal tells Erza that they will stay and finish the tower, in order to achieve real freedom by resurrecting Zeref. He then proceeds to kill the unconscious guards, surprising Erza. Despite that, Erza tries to convince Jellal to leave but he attacks her and tells her that she is free to leave but he will not allow the others to leave with her. Erza tries to reason with Jellal but Jellal uses Magic to hurt her, causing her to cry. He then orders her to leave and not to tell anyone about the tower or he will kill her friends.
With Erza gone, Jellal uses his Magic to cause the ships to explode, trapping the slaves on the island. He then tells them that Erza betrayed them and was driven mad with her new found power. He then manipulates them into finishing the tower, trapping them on the island for eight years.