1411, Donald secured Dingwall Castle which was the principal seat of the Earldom of Ross, after he had defeated the powerful Clan Mackay who were supporters of the Stewart confederacy at the Battle of Dingwall. This in turn resulted in the indecisive Battle of Harlaw on 24 July 1411 fought between Donald of Islay's forces and those of Robert Stewart, Duke of Albany. There may have been as many as 10,000 men in the army of Donald at the Battle of Harlaw, but he failed to inflict a decisive victory and withdrew back to the Western Highlands. In the aftermath, Albany was able to retake Dingwall and seize control of Easter Ross. By 1415 the Earldom of Ross was with Murdoch Stewart, Duke of Albany. Donald prepared for war and proclaimed himself "Lord of Ross". However, the Duke of Albany appointed his own son John Stewart, 2nd Earl of Buchan as the new Earl of Ross. In 1429 the Battle of Lochaber took place where forces led by Alexander of Islay, 3rd Lord of the Isles fought against the royalist army of James I of Scotland. Two years later the Battle of Inverlochy (1431) took place; While chief Alexander of Islay, Lord of the Isles was imprisoned by King James I, the Clan MacDonald were led by his nephew, Donald Balloch MacDonald, who defeated Alexander Stewart, Earl of Mar's royal army.<ref>{{cite book |last=MacDonald |first=Hugh |year=1914 |title=History of the MacDonalds, in Highland Papers |volume=I}}</ref> The armies of the MacDonald Lords of the Isles were the only magnate forces in Scotland capable of inflicting defeats on the Crown at this time. The Battle of Inverlochy in 1431 is one example of this and the Battle of Lagabraad in Ross in 1480 is another. Later in the 15th century the MacDonald chiefs would succeed as the Earls of Ross: firstly Alexander of Islay, Earl of Ross, son of Donald of Islay and Mariota, Countess of Ross, succeeded to the earldom as confirmed by a charter dated September 1437, following the assassination of James I of Scotland in February of the same year. Secondly, Alexander's son John of Islay, Earl of Ross who surrendered the earldom in 1475 to the King. According to 17th century historian Sir Robert Gordon, 1st Baronet who himself was a younger son of Alexander Gordon, 12th Earl of Sutherland, in 1455 the Battle of Skibo and Strathfleet took place