Clan Sweeney supporters of the powerful MacDougall Lords of Lorne who supported John Balliol as patriots, as long as John was king of Scotland. After the murder of John Comyn, the nephew of Balliol, by Bruce in 1306, the First War of Scottish Independence became at one and the same time a civil war. The Balliol and Comyn parties taking the side of the English in opposition to Bruce, crowned Robert I of Scotland on 25 March 1306. This was an era of constantly shifting alliances, and in 1301 John MacSween was in alliance with Aonghus Óg Mac Domhnaill, Lord of Islay
Christopher Seton letter of excommunication was issued naming the Earl of Carrick and three other knights, Sir Alexander Lindsay, Sir Christopher and his brother John Seton as John Comyn's murderers. Seton was also present at the coronation of his brother in-law King Robert I, King of Scots, at Scone on 25–26 March 1306. Some accounts have him present at the Battle of Methven on 19 June 1306 but Duncan places him at Loch Doon Castle, an important castle for the Earls of Carrick and one of three that Robert tried to hang on to, but Loch Doon fell about 14 August. Loch