As Earl of Angus he was summoned in 1276 for a campaign in Gwynedd against Llywelyn ap Gruffudd. In 1284 he attended the parliament with other Scottish noblemen who acknowledged Margaret of Norway as the heir to King Alexander. In 1296 he again joined Edward I in his conquest of Scotland.
The Earl of Angus was called upon by King Edward in 1276 to lead a military campaign against Llywelyn ap Gruffudd in Gwynedd. Two years later, he attended the Scottish parliament alongside other prominent nobles who acknowledged Margaret of Norway as the successor to Alexander. In 1296, he joined forces with Edward I once more as Scotland was conquered.