Born around 1280, son of Robert de Brus, Earl of Carrick by right of his wife, Edward's mother, Marjorie, Edward fought alongside Robert in the wars against Edward I, and Edward II of England, and their Balliol puppet-kings. Their three younger brothers, Niall, Thomas and Alexander, were all captured and killed by the English, Edward survived, and fought on, commanding part of the Scots army at the battle of Bannockburn in 1314.
In 1315, supported by Robert, by then declared king of Scotland, Edward answered a request for aid from Domhnall mac Brian O Neill, King of the Irish kingdom of Tir Eoghain. Domhnall was troubled by English agression from his south-east, east and west. Perceiving a common cause, Robert (as then without legitimate heir) declared Edward his successor as King of Scotland, and released him to assist the Irish. Edward landed, in the Larne area (whilst Robert was campaiging in the Western Isles) and defeated an Anglo-Irish force backed by the English Earl of Ulster, and in June Domhnall and twelve other Irish kings swore fealty to Edward as King of Ireland (although other Irish kings refused to submit to him). In Jury Edward held off an English army under Ulster and the King of Connaught and in the following weeks, by battle and by diplomacy to other Irish leaders, was able to drive Ulster back to the Connacht lands.
Edward of England sought to rally support but, despite sending the then-numinous Roger Mortimer to Ireland, Edward Bruse crushed the English at the Battle of Kells in Novermber. In 1316 and 1317 although sporadic warface continued, the great famine which struck Eurpoe at this time restricted the ability of either side to feed soldiers in the field.
Late in 1318 Sir John de Bermingham led an English army to Ireland and in a single battle (Faughart) destroyed Edward's forces, and captured and executed him. Restrospectively Edward was painted as having brought death and destruction to Ireland and having achieved little. This was a view supported by the English lords and their tenants, who thereafter were to strive to prevent any further attempt by the native Irish to unite under a single leader.