Until Gof Cadarn attempted to kill Maddox and revealed his apparent invincibility, it was assumed that there had been several Maddox's and that it was either a family name or some sort of title.
~80 years ago
Maddox the Red was a powerful warlord, powerful enough that he commanded the services of several lesser warlords and styled himself as a War King even outside the usual threat of a common enemy.
The prevailing theory is that Maddox used the war against the dwarves to become War King and that he then leveraged his position to maintain that power after the war ended.
~40 years ago
Gof Cadarn's home town was razed to the ground and his family killed in the attack. Based on information from Thaddeus Bargewright it seems likely that this attack was carried out by one of the warlords loyal to Maddox.
~5 years ago
Several ambassadors were dispatched from the Alvarium Kingdom to make diplomatic contact with Maddox as it was believed that united under a common leader the north could potentially join the more civilised nations. This proved to be a mistake when Maddox had all but one of the ambassadors beheaded, with the survivor being tortured and mutilated before being sent home.
Though generally a nomadic people it seems that Maddox had been capturing slaves and using them to construct a palace for himself complete with a semi-permanent settlement around it (Maddox's Palace).