‘After the deed was done (the slaying of Comyn), Bruce might be called desperate. He had committed an action which was sure to bring upon him the vengeance of all Comyn’s relations, the resentment of the King of England, and the displeasure of the Church, on account of having slain his enemy within consecrated ground. He determined, therefore, to bid them all defiance at once, and to assert his pretensions to the throne of Scotland. He drew his own followers together, summoned to meet him such barons as still entertained hopes of the freedom of the country, and was crowned King at the Abbey of Scone, the usual place where the Kings of Scotland assumed their authority.’
From Walter Scott’s "Tales of a Grandfather". Robert Bruce became King of Scotland on March 25th, 1306.