He was court-martialled and under sentence of death for the killing of two fellow officers before he escaped to serve in the Prussian army and was subsequently pardoned.
[2] Meanwhile, St Clair, was returned on his father's interest as Member of Parliament for Dysart Burghs at the 1708 British general election in May.
[2] Sinclair avoided punishment by escaping from camp with the connivance of the John Churchill, 1st Duke of Marlborough who arranged his enlistment in the service of King Frederick I of Prussia where he served for the rest of the war.
A critic of the Earl of Mar's leadership, he left the Jacobite headquarters at Perth shortly after the battle, following Alexander Gordon, Marquess of Huntly, northwards before fleeing to Kirkwall Castle and from there to the continent.
[2] He was succeeded in his title by his younger brother James, a general in the British Army and Member of Parliament for forty years.