 Another conflict that could have involved Ímar and the military forces of Dublin was Gruffudd 's final defeat of Hywel ab Edwin , King of <unk> ( died 1044 ) . According to <unk> y <unk> and the " B " version of <unk> <unk> this last stand of Hywel took place at the mouth of the River <unk> — perhaps in the vicinity of <unk> — and included Vikings from Ireland who supported Hywel 's cause . It is apparent that Gruffudd 's adversaries generally utilised foreign military support from Ireland 's Viking enclaves . Certainly , the Book of Llandaff declares that Gruffudd struggled against English , Irish , and Vikings during his career . 
