The reputation of John Erskine, nth Earl—and in the Jacobite Peerage 1st Duke—of Mar, has never stood very high. The incompetence that he showed as leader of the rising of 1715 left him but a scanty title to fame, and his conduct during the sixteen years which he spent in exile was so bitterly criticised by his enemies within the Jacobite party that he is generally remembered only for the ineptitude he displayed as a military commander and political conspirator. Even when anything is known of his subsequent career, it is usually something to his discredit, and the old stories are still in circulation: indeed, the latest biographers of The Old Chevalier go so far as to describe Mar as a “rat,” and call him the “evil genius” of his master. A study of some of the sources for Jacobite History after the '15, and particularly of the Stuart MSS. at Windsor Castle, seems to suggest, however, that Mar has been somewhat maligned and misunderstood in the past. The Stuart Papers, now in part printed by the Historical Manuscripts Commission, certainly throw fresh light on many aspects of Jacobite politics, and in this age of “Historical Revisions” it is but just that Mar should receive his due measure of attention.