in 1475, john of islay, earl of ross, chief of clan donald, forfeited the macdonald earldom of ross to james iii of scotland and although the macdonald lordship of the isles was not forfeited until 1493, in many ways 1475 marked the end of the lordship as a potent force. john of islay's natural son, aonghas óg (angus), was at feud with kenneth mackenzie, 7th of kintail, chief of clan mackenzie, and believed that the mackenzies intended to acquire the earldom of ross. angus therefore gathered a large force from the isles as well as men from the clan macdonald of keppoch and the clan macdonell of glengarry, and set out for ross. the government realizing that they faced a rebellion of some magnitude commissioned john stewart, 1st earl of atholl to set out and subdue it.