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. Added to this was a request for aid from the King of Tír Eógain (Tyrone), Domnall mac Brian Ó Néill (Donall Ó Néill). Ó Néill had been troubled by Norman incursions to the southeast (the de Verdons), the east (tenants of the Earl of Ulster) and west (also by the Earl of Ulster) of Tír Eógain and to retain his lands, he and some twelve of his vassals and allies jointly asked for aid from Scotland. The Bruce brothers agreed, on condition that Edward would be supported as King of Ireland. The brothers envisaged themselves as separate rulers of Scotland and Ireland. Robert would regain Man and Edward possibly make an attack on Wales, with Welsh support. Their vision included "a grand Gaelic alliance against England" between Scotland and Ireland, both countries having a common heritage, language and culture. When Ó Néill approved of conditions for himself and on behalf of his vassals, preparations began. Roger Mortimer, 3rd Baron Mortimer, received news from Irish sources around this time that an invasion was about to take place, and made his way to Ireland, where he held land mainly in and around the castle and town of Trim. He had previously fought against the Bruces at Bannockburn where he was taken prisoner and freed to return King Edward II's royal seal, lost in the rout. The Scottish Parliament met at Ayr on 26 April 1315, just across the North Channel from Antrim. As King Robert did not yet have a legitimate son, Edward was proclaimed his legal heir and successor as King of Scots and all other titles in case of his death. Edward's invasion fleet also mustered there, having received calls to assemble as far back as at least the previous month. On 26 May 1315 Edward and his fleet (and more than 5,000 men) landed on the Irish coast at points at and between Olderfleet Castle at Larne, and Glendrum.