[2] Much of what is known about the childhood of Hattusili III is gathered from a biographical account, written on a stone tablet during his reign, referred to as the Apology.

[3] Hattusili III was born the youngest of four children to the Hittite king Mursili II and queen Gassulawiya.

When his brother Muwattalli II became king, Hattusili III was appointed to govern over the northern lands of the Hittite empire.

While this initially caused minor controversy among the locals and the ousted governor, Hattusili III was quick to quash dissidence with military force[7] and turned his eyes towards conquering new territories surrounding the northern Hittite lands.

Shortly after his accession to the throne, Mursili III had the capital moved from Tarhuntassa back to its original home of Hattussa.

[2] Hattusili's reign as king is notable for the large collection of letters and written accounts unearthed from this period.