[2] He later reigned as king Osorkon III in Upper Egypt for twenty-eight years after defeating the rival forces of Pedubast I/Shoshenq VI who had apparently resisted the authority of his father here.

Osorkon ruled the last five years of his reign in coregency with his son, Takelot III, according to Karnak Nile Level Text No.

[5] The issue is complicated by the fact that Prince Osorkon B did not immediately declare himself king after his successful conquest of Thebes and defeat of Shoshenq VI.

Osorkon III is attested by numerous impressive donation stelae and stone blocks from Herakleopolis Magna through to Thebes.

Secondly, according to Ōhshiro Michinori,[6] Anthony Leahy,[7] and Karl Jansen-Winkeln,[8] an important donation stela[9] discovered in 1982 at Ṭihnā al-Ǧabal (ancient Akoris) reveals that Osorkon III was once a High Priest of Amun in his own right.

This theory has now been accepted by many Egyptologists, including Jürgen von Beckerath,[10] Karl Jansen-Winkeln,[11] Gerard Broekman,[12] and Aidan Dodson, among others, with the notable exception of Kenneth Kitchen.

[14]Osorkon probably lived into his eighties, which explains why he appointed his son Takelot III as the junior coregent to the throne in his final years.