defeat, Edward retreated to Dunbar, then travelled by ship to Berwick, and then back to York; in his absence, Stirling Castle quickly fell. Mid-reign (1314–1320) Further confrontation with England then the Irish conflict Freed from English threats, Scotland's armies could now invade northern England. Bruce also drove back a subsequent English expedition north of the border and launched raids into Yorkshire and Lancashire. Buoyed by his military successes, Robert also sent his brother Edward to invade Ireland in 1315, in an attempt to assist the Irish lords in repelling English incursions in their kingdoms and to regain all the lands they had lost to the Crown (having received a reply to offers of assistance from Domhnall Ó Néill, king of Tír Eoghain), and to open a second front in the continuing wars with England. Edward was even crowned as High King of Ireland in 1316. Robert later went there with another army to assist his brother. In conjunction with the invasion, Bruce popularised an ideological vision of a "Pan-Gaelic Greater Scotia" with his lineage ruling over both Ireland and Scotland. This propaganda campaign was aided by two factors. The first was his marriage alliance from 1302 with the de Burgh family of the Earldom of Ulster in Ireland; second, Bruce himself, on his mother's side of Carrick, was descended from Gaelic royalty in Scotland as well as Ireland. Bruce's Irish ancestors included Aoife of Leinster (d.1188), whose ancestors included Brian Boru of Munster and the kings of Leinster. Thus, lineally and geopolitically, Bruce attempted to support his anticipated notion of a pan-Gaelic alliance between Scottish-Irish Gaelic populations, under his kingship. This is revealed by a letter he sent to the Irish chiefs, where he calls the Scots and Irish collectively nostra nacio (our nation), stressing the common language, customs and heritage of the two peoples: The diplomacy worked to a certain extent, at least in Ulster, where the Scots had some support. The Irish chief, Domhnall Ó Néill, for instance, later justified his support for the Scots to Pope John XXII by saying "the Kings of Lesser Scotia all trace their blood to our Greater Scotia and retain to some degree our language and customs." Initially, the Scot-Irish army seemed unstoppable as they defeated the English again and again and levelled their towns. However, the Scots failed to win over the non-Ulster chiefs or to make any other significant gains