Battle in the Void

The Battle in the Void was the final conflict of the End War, where the forces of the Koprulu Sector entered the Void through Ulnar in order to finally destroy Amon. It ended with the defeat of Amon and the end of the Infinite Cycle, and paved the way for a brief period of peace to allow the sector to begin reconstruction.

Background
Through the actions of Hierarch Artanis on Aiur, Amon's host body was destroyed, and using the Keystone he was forced from the Khala and back into the Void. However, he still existed within the Void, and would eventually return. Zerg queen Sarah Kerrigan began hearing voices from the Void calling to her, but not from Amon, rather from a benevolent source. She called to Artanis and Commander Jim Raynor of the Terran Dominion, and told them to meet her at Ulnar. There she explained the situation to them, and they agreed that they could not allow Amon to continue to exist within the Void; they had to finish him once and for all.

Battle for the Locks
However, Amon knew that forces would be upon him, and mustered the last of his forces int he material universe to overload the locks on Ulnar, thus destroying the temple and cutting off the Koprulu Sector's forces access to the Void. Under the supervision of Grand Preserver Rohana, two commanders defended the locks, securing them so that Amon could not overload them. During the battle, Amon sent a xel'naga construct that he had twisted to his will against them. The commanders were successful in defending the locks, and clearing the way for the Koprulu commanders to enter the Void.