War on Two Fronts
No king exercised uncontested government over the whole island. Donnchad mac Briain, son of Brian Bórama, ruled much of Munster and had previously extracted hostages from several kingdoms. His prestige was nevertheless declining. Diarmait mac Máel na mBó, king of Leinster and Uí Chennselaig, had seized control of Dublin in 1052 and was building a formidable combination of Leinster military strength, Norse-Gaelic maritime resources and alliances beyond his own province.