In 1315 Robert the Bruce, King of Scots, sent his younger brother Edward Bruce to invade Ireland. There have been several theories as to the motives behind Bruce's campaign in Ireland. One theory is that Robert the Bruce saw Ireland as a fellow Gaelic, Celtic nation with both Scotland and Ireland sharing common origins, with the Bruces also claiming Irish ancestry themselves from Aoife MacMurrough, and as such saw it as his duty to liberate the island of English control. Another theory proposed for the invasion of Ireland was to drain England of men, materials and finance and even to exploit the resources in Ireland for Scotland's benefit, a second front in the ongoing war, as England relied heavily on Ireland for resources and deprive the English of Irish tax revenues contributing to the war effort. This became critical when King Robert's control of the Isle of Man was lost to Norman-backed Scots in January 1315, opening a threat to the south and southwest of Scotland, and also reopening up a potential source of aid to England from the Hiberno-Normans and Gaelic Irish.