Clan Donnachaidh the Battle of Methven in 1306. The clan asserts that Stout Duncan's relatives and followers (not yet known as Robertsons) supported Robert the Bruce at the Battle of Bannockburn in 1314. His descendants became known (in English or Scots) as the Duncansons, or Gaelic "Clann Dhònnchaidh", "Children of Duncan". Duncan is believed to have been killed at the Battle of Neville's Cross and was succeeded by Robert, from who the Clan Robertson takes its name. Robert's brother, Patrick, was the ancestor of the Robertsons of Lude who were the principal cadet branch. In 1394 a clan battle took place between
Robert the Bruce planned a major military campaign with the support of Lancaster and the barons, mustering a large army of between 15,000 and 20,000 men. In the spring of 1314, Edward Bruce laid siege to Stirling Castle, a key fortification in Scotland whose governor, Philip de Mowbray, agreed to capitulate if not relieved before 24 June 1314. In March, James Douglas captured Roxburgh, and Randolph captured Edinburgh Castle, while in May, Bruce again raided England and subdued the Isle of Man. News of the agreement regarding Stirling Castle reached the English king in late May, and he decided to speed his march