Meanwhile, Robert the Bruce exploited his victory at Bannockburn to raid northern England, initially attacking Carlisle and Berwick, and then reaching further south into Lancashire and Yorkshire, even threatening York itself. Edward undertook an expensive but unsuccessful campaign to stem the advance in 1319, but the famine made it increasingly difficult to keep his garrisons supplied with food. Meanwhile, a Scottish expedition led by Robert's brother Edward Bruce successfully invaded Ireland in 1315. Edward Bruce declared himself the King of Ireland. He was finally defeated in 1318 by Edward II's Irish justiciar, Edmund Butler, at the Battle of Faughart, and Edward Bruce's severed head was sent back to Edward II. Revolts also broke out in Lancashire and Bristol in 1315, and in Glamorgan in Wales in 1316, but were suppressed.