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.
As Earl of Angus, he participated in a military expedition against Llywelyn ap Gruffudd in Gwynedd in 1276. He also attended parliament in 1284 alongside other Scottish nobles who recognized Margaret of Norway as the rightful heir to Alexander. In 1296, he collaborated with Edward I during Scotland's conquest.