 In 863 the three brothers raided Brega in alliance with Lorcán, and the following year Amlaíb drowned Conchobar at Clonard Abbey.Muirecán mac Diarmata, overking of the Uí Dúnchada, was killed by Vikings in 863, probably by Amlaíb and his kin trying to expand into Leinster.Beginning around 864 the three brothers halted their campaigns of conquest in Ireland, and instead campaigned in Britain.