When Llywelyn refused to do homage following a number of disputes with the king, Edward launched a ferocious campaign to drive the Welsh back into their heartland of Gwynedd.
Pan wrthododd Llywelyn dalu gwrogaeth ar ôl nifer o anghydfodau â’r brenin, lansiodd Edward ymgyrch ffyrnig i yrru’r Cymry yn ôl i’w perfeddwlad yng Ngwynedd.