Amenmesse

Menmire Setepenre was his royal name. He was most likely not Merneptah’s planned heir. Kenneth Kitchen and Jürgen von Beckerath think Amenmesse took the throne from Seti-Merneptah, Merneptah’s son and crown prince, who should have been the next in line to the throne. It’s impossible to say how this may have happened. According to Kitchen, Amenmesse may have taken advantage of Seti-sudden Merneptah’s weakness or seized power when the crown prince was travelling in Asia. Seti-Merneptah was almost certainly the same person as King Seti II, whose reign was considered to have succeeded that of Amenmesse.
Seti II’s tomb cartouches in Upper Egypt were purposefully removed and then repainted, implying that Seti’s power in Upper Egypt was briefly disrupted by agents of his half-brother. Amenmesse’s reign and place in Egypt’s 19th Dynasty are both shrouded in mystery. However, a growing number of Egyptologists, like Rolf Krauss and Aidan Dodson, believe that Seti II was Merneptah’s direct successor “without any interim administration by Amenmesse.” In this scenario, Amenmesse was not Merneptah’s successor on the Egyptian throne, but rather a rival king who stole power in Upper Egypt and Nubia during Seti II’s reign, where his authority is monumentally proven.
Amenmesse was in power at Thebes throughout his third and fourth years (and maybe earlier in Nubia), but Seti II’s third and fourth years are clearly missing. The portrayal of Amenmesse as a rival king also explains the sequence of damage at Seti II’s tomb, which was first looted and then reconstructed by Seti II’s officials. This suggests that Amenmesse’s and Seti II’s reigns ran concurrently; Seti II must have ruled Thebes during his first and second years, during which time his tomb was dug and partially painted. Then, in Upper Egypt, Seti was deposed by Amenmesse, whose agents desecrated Seti II’s tomb. Seti would eventually vanquish Amenmesse and triumphantly return to Thebes, where he ordered the rebuilding of his ruined tomb.