The brother of *Muwatallis, Khattusilis III held great authority over the north-eastern provinces of the kingdom. Urhi-Teshub, (*Muwatallis' son and successor), sought to curtail this power, but after seven years Khattusilis III seized the Hittite throne from Urhi-Teshub and justified this action in an extensive document which is sometimes known as his 'Autobiography'.
His reign was marked by peace and prosperity and he is remembered for the famous treaty which he concluded with *Ramesses II, in Year 21 of the latter's reign (1269 BC). This treaty is the only one which has been discovered to date, although others were enacted between various Near Eastern rulers; it guaranteed peace and security for Egypt, the *Hittites and their vassal states in the Syria-Palestine region. It has survived in two versions: the Egyptian one is inscribed on a stela in the Temple of Karnak, while the *Hittite copy was discovered, in a less complete form, on two clay tablets in the archive at Boghazkoy, the *Hittite capital.
In such treaties the participants were equals and sought 'brotherhood' with each other; it was both a defensive and an offensive alliance and reaffirmed an earlier agreement made in the reign of *Suppiluliumas. It removed the possibility of war, with both parties agreeing not to encroach on each other's territory and to aid each other in the event of attack by a third power; it also provided for the equal extradition of refugees but insisted that they should be well-treated. In the Egyptian version, the gods of both lands were invoked as witnesses.
This treaty led to cordial relations and the exchange of correspondence between the two kings and their respective queens; thirteen years later the alliance was cemented by a marriage between *Ramesses II and a daughter of Khattusilis and his queen, Pudukhepa. Inscriptions on the walls of various Egyptian temples related the story of the *Hittite princess' arrival in Egypt; she was subsequently renamed Manefrure and found sufficient favour with *Ramesses II to become his Great Royal Wife.
BIBL. Langdon, S. and Gardiner, A.H. The Treaty of Alliance between Hattusili, king of the Hittites, and the Pharaoh Ramesses II of Egypt. JEA 6 (1920) pp. 179 ff; Gurney, O.R. The Hittites. Harmondsworth: 1964.
Biographical Dictionary of Ancient Egypt by Rosalie and Antony E. David
Ancient Egypt. A Reference Guide. EdwART. 2011.